Calculate due date based on last period

Pregnancy Due Date Calculator | BabyCenter

Calculation method

When did your last period start?

mm-dd-yyyy

Cycle length

BabyCenter's Due Date Calculator

Use our pregnancy due date calculator by plugging in either the date of your last menstrual cycle or the date you know you conceived. The calculator will do the rest.

How is my due date calculated?

There are several ways your due date is determined. If you happen to know the day you conceived, you can count 38 weeks from that day to find your due date. (Human gestation takes about 38 weeks.)

But very few expectant moms know exactly when they conceived. Even if you only had sex once during your fertile period, you wouldn't conceive on that day unless you happen to be ovulating. Sperm can live for up to five days inside your fallopian tubes. So, it could be up to five days after you have sex that you release an egg (ovulate) and it gets fertilized by a waiting sperm. That's the day you conceive.

So, without knowing the day of conception, how does anyone determine a due date?

First day of your last period

The most common way to calculate your pregnancy due date is by counting 40 weeks from the first day of your last menstrual period (LMP). And that's how most healthcare providers do it.

If your menstrual cycle length is the average length (28-day cycle), your menstrual cycle probably started about two weeks before you conceived. This explains why pregnancies are said to last 40 weeks instead of 38 weeks.

This method doesn't take into account how long your menstrual cycle actually is or when you think you might have conceived. But generally speaking, women typically ovulate about two weeks after their menstrual cycle starts. And women are more likely to know when their last period started than the day they ovulated.

Conception date

If you do happen to know precisely when you conceived – say, if you were using an ovulation predictor kit or tracking your ovulation symptoms – you can calculate your pregnancy due date based on your conception date. Just choose that calculation method from the pulldown above and put in your date.

Note: Again, you don't necessarily conceive on the day you have sex.

IVF transfer date

If you conceived through IVF, you can calculate your due date using your IVF transfer date. If you had a Day 5 embryo transfer, count 261 days from your transfer date. If you had a Day 3 embryo transfer, count 263 days.

Can my due date change?

Your healthcare provider might revise your due date if your baby is measured during a first trimester ultrasound scan and found to be much bigger or smaller than expected for gestational age. This is more likely to happen if you have an irregular menstrual cycle length that makes it hard to pinpoint the date of conception. 

Your healthcare provider will measure your baby during that ultrasound exam to figure out how far along your baby is and then provide you with a new due date.

What if I already know my due date?

If you already know your due date, you can use this calculator to see your pregnancy timeline. It will tell you when you'll hit various milestones, and when you may be due for prenatal tests and prenatal visits. You'll also find what your baby's sign and birthstone will probably be and which famous people were born on your due date.

How likely am I to give birth on my due date?

Of course, a due date calculation is always approximate, whether it's from our tool or from your doctor or midwife. Only 1 in 20 women delivers on her due date. You're just as likely to go into labor any day during the two weeks before or after.

Want more information about how the weeks, months, and trimesters of pregnancy are counted? See our pregnancy timing chart.

How soon can I take a pregnancy test?

With all this talk about pregnancy due dates, you may be wondering when you can take a pregnancy test. To ensure you get the most accurate reading, it's best to wait a few days after your missed period to take a pregnancy test.

At-home urine tests measure the amount of hCG (human chorionic gonadotropin) present in your body. If you take a pregnancy test before you miss your period, you may not get an accurate result, despite what some tests advertise.

If you're getting a blood test in your provider's office, you may get results sooner. These tests also measure the amount of hCG in your bloodstream, but they're more sensitive than at-home urine tests. Blood tests may be able to detect pregnancy six to eight days after ovulation.

Read more:

• Your pregnancy, week by week
• Your first trimester pregnancy checklist
• Pregnancy Weight Gain Calculator
• Ovulation Calculator
• See all tools

BabyCenter Staff

Content that appears under this byline was created by members of the BabyCenter Editorial team.

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Highlights this week

Taking a pregnancy test

By the end of this week, you may be able to get a positive pregnancy test. Pregnancy tests work by detecting the presence of a hormone called human chorionic gonadotropin (hCG) in your urine. Some home pregnancy tests claim to detect pregnancy as early as five days before you miss your period, but it's best to wait until the first day of your missed period for accurate results. If you test too soon, you may get a false negative pregnancy test or an unclear result like a faint line.

Implantation

Your developing blastocyst has travelled down the fallopian tube and is starting to implant itself in the lining of your uterus. At this time, 15 to 25 percent of women experience implantation bleeding, which is a light bleeding that happens about six to 12 days after conception. You may feel implantation cramps as well.

Early pregnancy symptoms

Most women don't feel anything until they've missed a period, but you may notice bloating, cramping, or spotting this week. Your breasts may also be more tender than usual and you may have a heightened sense of smell, one of the earliest pregnancy symptoms. So if your partner, your house, or your dog suddenly smells different to you, thank your surging hormones.

Baby development at 3 weeks

Cells are multiplying

Your developing baby is a tiny ball of several hundred cells that are multiplying and burrowing into the lining of your uterus. The cells in the middle will become the embryo. The cells on the outside will become the placenta, the pancake-shaped organ that delivers oxygen and nutrients to your baby and carries away waste.

Connecting to you

Your baby-to-be is receiving oxygen and nutrients (and discarding waste) through a primitive circulation system made up of microscopic tunnels that connect to the blood vessels in your uterine wall. The placenta will eventually take over this task around the end of the first trimester.

Your baby at 3 weeks

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Implantation

3 weeks pregnant body

Early pregnancy hormones

The cells that will become the placenta are pumping out the pregnancy hormone hCG. It tells your ovaries to stop releasing eggs and keep producing progesterone, which prevents your uterus from shedding its lining – and its tiny passenger. Once there's enough hCG in your urine, you'll get a positive pregnancy test result.

Amniotic fluid

Amniotic fluid is beginning to collect within the amniotic sac. This fluid will cushion your baby in the weeks and months ahead, and it's what may eventually come gushing out of you if your water breaks before or during labor.

Pregnancy symptoms during week 3

No pregnancy symptoms?

Some women feel pregnant even before the test is positive, but most don't. If you have pregnancy symptoms this week, they may feel like PMS. But don't worry if you haven't felt anything different yet. Even at 5 weeks pregnant, only half of women feel pregnancy symptoms.

Gas and bloating

The hormone progesterone relaxes muscles throughout your body, including in your digestive tract. These relaxed muscles slow down your digestion, which can lead to gas and bloating and create uncomfortable sensations in your gut. About half of pregnant women experience constipation at some point during their pregnancy. To keep things moving, stay hydrated and eat high-fiber foods like whole grains, fruits, and vegetables.

Sore breasts

Some women say their sore breasts in early pregnancy are like an exaggerated version of how they feel before a period. Your breasts may feel swollen, tender, or tingly – and your nipples may be extra sensitive and uncomfortable. Later in pregnancy, you may notice your nipples getting darker.

Spotting

You may have a bit of light bleeding (spotting) this week. This is implantation bleeding – it can happen around the time the fertilized egg implants in your uterus. It's a lot lighter than a typical period, and only lasts for one to three days. (If you have pain along with bleeding, call your healthcare provider immediately. This can be a sign of an ectopic pregnancy.)

Basal body temperature stays high

If you're charting your temperature, it should stay elevated this week. To keep track, use a basal body thermometer and take your temperature after you wake up in the morning, before you get out of bed.

Your body at 3 weeks

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Pregnancy checklist at 3 weeks pregnant

Pay attention to your emotions

When you're waiting to learn whether you're pregnant or not, or just finding out, it's normal to be anxious. If you're feeling stressed or worried, talk to your partner or a trusted friend. Or, try writing down everything that's bothering you. Journaling can improve your emotional well-being, mental clarity, and even physical health.

Avoid overheating

Hot baths are okay during pregnancy as long as they aren't too hot. But avoid steam baths, hot tubs, and saunas. Elevated body temperature, especially early in pregnancy, has been associated with an increased risk of neural tube defects in babies.

Eat nutritious meals and snacks

Eat pregnancy-friendly foods such as fruits and vegetables, low-mercury fish, and whole grains. Choose foods containing vitamin C (like strawberries, citrus fruits, bell peppers, and tomatoes), iron (like beef, poultry, soy products, and spinach), and calcium (like Greek yogurt, fortified cereal, and pasteurized cheese). For snack ideas, check out 10 of our favorite healthy snacks for expecting moms.

Cut down on coffee

While you're trying to conceive and once you get pregnant, experts recommend limiting caffeine to about one cup of coffee a day. It's important to watch your caffeine intake because having too much can affect your pregnancy and your baby. See how much caffeine is in different foods and drinks so you can stay under the recommended daily limit.

Get help quitting

If you need help quitting smoking, drinking, or taking drugs, talk to your healthcare provider and ask for a referral to a program or counselor.

Improve your sleep

When pregnancy-related sleep problems hit in a few months, be ready for them. Create better habits around sleep and work on good sleep practices like establishing a regular bedtime routine and making your bedroom a sleep sanctuary.

Make sure your work and home are safe

Some jobs can be hazardous to you and your baby. If you're routinely exposed to chemicals, loud noises, or radiation at work, or if you have to be on your feet constantly or lift heavy objects, talk to your provider about how to stay safe while working during pregnancy. Also, keep in mind that some things in your home may be dangerous for your developing baby. Lead (in drinking water from old pipes), mercury (in certain fish), certain pesticides and fertilizers, and cat litter containing feces are all potentially harmful.

Kate Marple

Kate Marple is a writer and editor who specializes in health, pregnancy, and parenting content. She's passionate about translating complicated medical information into helpful pregnancy and parenting advice that's easy to understand. She lives in San Francisco with her family.

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〚 Pregnancy calculation.

Feb 11, 2020

Most pregnancies last around 40 weeks (or 38 weeks from conception), so generally the best way to determine your due date is to count 40 weeks or 280 days from the first day of your last period ( LMP). Another way to do this is to subtract three months from the first day of your last period and add seven days. So if your last period started on April 11th, you would count down three months to January 11th and then add seven days, which means your due date should be January 18th. This is how your doctor will estimate your due date - and that's a pretty solid goal. But remember: delivering a week or two before or after is just as normal.

Date of conception

Calculating due date based on the first day of your last period works well for women with relatively regular menstrual cycles. But if your cycle is irregular, the LMP method may not work for you. Because a reliable estimated due date (EDD) is important, you and your doctor can use your conception date if you remember it. Just add 266 days to get an estimate.

IVF transfer date

According to the Centers for Disease Control and Prevention (CDC), more than 250,000 assisted reproductive technology cycles are performed each year in the United States, resulting in about 77,000 or more babies born each year. If you are part of a growing tribe of IVF moms, you can more accurately calculate your due date using the IVF transfer date.

Ultrasound Scan

Even if you can't pinpoint when you conceived, forgot the day of your last period, or aren't sure when you ovulated, other clues can help you and your doctor determine your due date at your first pregnancy appointment, including :

Early ultrasound, which can more accurately determine the date of pregnancy. However, keep in mind that not all women get an early ultrasound. Some practitioners do them regularly, but others recommend only one if your periods are irregular, you are 35 or older, you have a history of miscarriage or pregnancy complications, or the due date cannot be determined based on your physical examination and LMP.

Pregnancy milestones, such as the first time the baby's heartbeat is heard (around 9 or 10 weeks, although this may vary) and when you first feel the baby move (between 18 and 22 weeks on average, but this may be earlier or later) may give clues as to whether your due date is accurate.

Your fundal height, which is measured from your pubic bone to the top of your uterus, is checked by your doctor at every prenatal visit and helps confirm your due date.

The size of your uterus, which will be noted during your initial internal pregnancy test, can also be a factor in determining EDD.

Can I schedule my due date?

Whether you're trying to avoid a midsummer pregnancy or you're a teacher who wants to have the most fun with your baby, you can try to determine when you'll get pregnant to "plan" your due date. But even if you're one of those lucky ones who can get pregnant when she really wants to, just remember that you probably won't be able to tell exactly when you'll give birth a day (or even a week). or a month!)

Can the due date change a lot?

Yes, your due date may change. While this is definitely not a cause for concern, your doctor may change your due date for a number of reasons as your pregnancy progresses. Maybe you're having irregular periods and an early ultrasound date was cancelled, or that your first ultrasound was in your second trimester. It may also be because you have abnormal growth or abnormal levels of alpha-fetoprotein (AFP), a protein produced by your baby. Talk to your practitioner if you have any questions or concerns.

How to calculate the estimated due date. How to determine the date of delivery: methods

Determining the duration of pregnancy and the estimated date of delivery is very important for both the woman and her doctor. Many laboratory and instrumental studies are prescribed precisely at the time when it is easiest to identify the pathology in time. Comparison of fetal parameters with the average statistical indicators of each period of pregnancy helps to identify and correct underdevelopment. Clarity in determining the date of birth of a child allows you to carefully prepare for this event and open a sick leave in time so that the woman has time to gain strength before childbirth.

There are several methods to help calculate the required indicators. An obstetrician-gynecologist uses them in combination, since almost every method has an allowable error associated with subjective reasons: the individual characteristics of a woman, elementary forgetfulness - it is difficult to remember the date of the last menstruation. The term of the expected birth can be determined quite approximately, since a full-term pregnancy lasts from 38 to 42 weeks, and this is normal from the point of view of physiology.

Naegele's Formula

The method of calculating due date using this formula is excellent for women with a regular standard cycle of 28 days. Negele's formula is simple - to determine the desired date, you need to subtract 3 months from the first day of the last menstruation, and then add 7 days to the resulting figure. If the menstrual cycle was constant, but lasted more or less than the standard one, the difference between your own and the standard cycle should be added to the date obtained, or the same number of days should be subtracted.

How to calculate due date by ovulation date?

If a woman in the month before conception determined the onset of ovulation by basal temperature, this will help to accurately determine the gestational age. Conception occurs on the day of ovulation, when the egg ready for fertilization leaves the ovary. If sexual intercourse took place 1-2 days before ovulation, spermatozoa remain ready for fertilization all this time, that is, conception can occur a short time after sexual contact. If you add 38 weeks, or 266 days, to the date of ovulation, you can find out the estimated date of birth of the child.

If a woman does not know when she ovulated, but has a stable 28-day menstrual cycle, it is assumed that conception occurred in the middle of the cycle, that is, on day 14. With an irregular cycle, this method has an error.

Determine the date by the movement of the baby

The date when the woman first felt the movement of the baby is very important for correcting the complex calculation of the term of the expected birth. Although the fetus begins to move as early as the twelfth week, for the first time most women feel these gentle movements in the middle of the gestational period, that is, in the twentieth week. However, this rule does not apply to everyone - during the second and subsequent pregnancies, a woman may feel the first movements 2 weeks earlier.

A primiparous woman of a fragile constitution also has this possibility, while a pregnant woman with a solid build feels movements later. These sensations can be called subjective, because they depend on the woman's sensitivity to what is happening in her body. The thickness of the myometrium also affects the severity of the movements of the child.

All these nuances mean that the above method of determining the date of birth cannot be considered the main one, it is used only in combination with other methods.

How do obstetricians and gynecologists calculate the gestational age?

When calculating the duration of pregnancy, the doctor usually relies on the date of the beginning of the last menstruation, however, the main calculations are carried out taking into account a complex of various criteria.

By uterine size

In the early stages of pregnancy, when individual differences in fetal size are not yet apparent, the due date can be determined using this method. For a period of 4 weeks, the size of the uterus is compared with a chicken egg, for a period of 8 weeks - with a goose.

From the twelfth week, this method is already difficult to apply, since later on the parameters of the uterus and fetus differ in different women with the same period.

Ultrasound

Ultrasound-based due date is valid at the beginning of the gestational period, more precisely up to the third month. After twelve weeks, it is impossible to accurately determine the date of birth based on ultrasound data due to individual differences in fetal parameters in women of different constitutions.

Fundal Height

This method has been used by the OB/GYN since the beginning of the second trimester. The longer the fetus develops, the higher the bottom of the organ becomes, which rises beyond the small pelvis.

Fundal height is determined when the woman is lying on her back. The doctor carefully palpates the abdomen and measures the distance from the pubic symphysis to the fundus of the uterus. This indicator increases evenly throughout the gestational period, and immediately before childbirth, the uterus descends.

When using this technique, an error of 2-3 cm is laid. It can be caused by polyhydramnios, pregnancy with twins or triplets, the age of the woman, the size of the fetus. To clarify the indicators, the waist circumference of the pregnant woman and the parameters of the fetus are taken into account.

Fundal height calculation by week:

8-9 weeks - height 8-9 cm, the uterus is still located within the small pelvis;

10-13 weeks - height 10-11 cm, the uterus increases, the placenta develops intensively, the fetal cardiovascular system begins to work;

16-17 weeks - height 14-18 cm, the uterus is located between the navel and the pubic joint, the fetus looks like a little man, all the organs of which are already laid;

18-19 weeks - height 18-19 cm, the unborn child develops arms and legs with fingers, cerebellum, immune system, the placenta takes full responsibility for ensuring the functioning of the fetus;

20 weeks - the height of the uterus in centimeters corresponds to the gestational age in weeks;

21 weeks - height 21 cm, from now on the height of the uterus will increase by 1 cm weekly, now it is 2 fingers below the navel.

22-24 weeks - height 22-24 cm, the bottom of the uterus at the level of the navel, easily determined by palpation, the body weight of the fetus is 0.6-0.7 kg;

25-27 weeks - height 25-28 cm;

28-30 weeks - height 28-31 cm;

32 weeks - height 32 cm, the upper edge of the uterus is located between the xiphoid process of the sternum and the navel;

36 weeks - height 36-37 cm, the uterus is palpable at the line of connection of the costal arches;

39 weeks - height 36-38 cm, the uterus begins to descend, the weight of the fetus exceeds 2 kg;

40 weeks - the height of the uterus decreases to 32 cm, it is again between the navel and the ribs, the baby is ready for delivery.

According to the size of the head and length of the fetus

The following methods are used to calculate the gestational age:

Jordania method. The term is calculated according to the formula X=L+C, where X is the term in weeks, L is the length of the body of the fetus (cm), C is the diameter of its head (cm).

Skulsky method. Here the formula is: X=(L x 2) - 5/5, where L is the length of the fetal body (cm), the number 5 in the numerator of the fraction is the thickness of the myometrium, the number 5 in its denominator is a special coefficient.

Any calculations are only a rough guideline. According to medical statistics, only 10-17% of babies are born on time, the rest are born earlier or later than the expected date. This circumstance is influenced by many factors: heredity, pregnancy pathologies, stressful situations and other reasons.

How to know the due date? About the method for calculating the due date

For calculating the expected due date obstetrician-gynecologists have a very convenient and simple formula: 9 months and 7 days are added to the date of the first day of the last menstruation. And you can calculate even easier - from the first day of the last menstruation, count back 3 months and add 7 to the resulting number.

Estimated due date = first day of last menstrual period + 9 months + 7 days.

Estimated due date = first day of last menstrual period - 3 months + 7 days.

But these terms are typical for the average woman with an average 28-day menstrual cycle and ovulation on the 14-15th day of the cycle.

The average pregnancy lasts 266 days (38 weeks) from conception, or 280 days (40 weeks) from the first day of your last period. If the menstrual cycle of the future mother is shorter or longer than the average 28 days, or ovulation did not occur on the 14-15th day of the cycle, then the pregnancy can also be longer or shorter. Therefore, it is generally accepted that 280 days is the approximate number of days of pregnancy and a child can be born between the 266th and 294th day (38–42 weeks) of pregnancy.

Calculation of the date of delivery by the day of conception is not an accurate method for determining the due date. Even if you know exactly the day when sexual intercourse took place, this does not mean that conception occurred on that day, since spermatozoa are able to remain active in the vagina for up to several days.

How else can I determine the gestational age and calculate the due date?

In the early stages, up to 12 weeks of pregnancy, the date of delivery can be calculated quite accurately using ultrasound. Over long periods, this is often difficult due to the fact that each child grows at his own pace. Namely, such indicators as the sizes of different parts of the fetal body are the basis for calculating the gestational age.

During pregnancy, the uterus begins to gradually increase in size and takes on a spherical shape. With a gynecological examination up to 12 weeks, the doctor can determine the approximate gestational age by the size of the uterus. For periods of more than 16 weeks, when the uterus extends beyond the womb, you can determine the period by the height of the standing of the bottom of the uterus during examination of the abdomen. Naturally, this method of determining the gestational age is not accurate.

Another auxiliary method for determining the gestational age and calculating the due date is by movement. Despite the fact that the child begins to make movements quite early, the mother can only feel them when the baby reaches a certain weight. This usually happens in nulliparous women at 18-20 weeks of gestation, and in multiparous women 2 weeks earlier. However, some women claim that they feel movements as early as the 14th week and sometimes earlier.

Using all of the above methods, you can more or less accurately determine the gestational age, but the date of delivery will still be approximate. This means that the chance of giving birth on the due date +/- 3 days is about 70%. Do not forget that the child's readiness for extrauterine life also affects the date of birth. Some children of the so-called morpho-functional maturity can reach the 38th week, while others - at the 41st.

All pregnant women know modern ways to calculate the due date. The approximate date of birth of the child can be found out (calculated) and checked in advance.

For every expectant mother during pregnancy, the most important thing is not her birthday, but the date of birth, which can be calculated today with a small error.

There are several different ways, methods, techniques, how to find out the date of birth. They are based on the well-known physiological features of the course of pregnancy. It is known, in particular, that on average, a normal pregnancy lasts about 40 weeks, if we count from the beginning of the last menstruation. Absolutely accurately calculate the date of birth, of course, is impossible. The duration of pregnancy is different for all women. But all pregnant women know how to correctly calculate the expected date of birth. The error is most often a few days.

Methods and methods of calculation

How to calculate the due date? It is possible, for example, to determine the date of birth by the date of conception, if there is reason to more or less accurately assume on which day it occurred. From the date of conception, respectively, just count the duration of pregnancy.

What is a DA, what is an “online calculator”?

EDD - estimated date of delivery. In order to determine it, you can, among other things, use the so-called "calculators", which are also available online today. Each such service on the Internet has instructions on how to determine the gestational age, how to calculate the date of birth (DDR) for the last menstruation. You can do this in just a few seconds.

Definition of DA

You can calculate the expected date of birth not only with the help of a calculator on the Internet, but also on your own. There are several ways. All of them have an error, but with a competent calculation, it is possible to calculate the estimated date of birth with an accuracy of up to a week.

Does the date of delivery depend on the characteristics of the menstrual cycle?

The date of delivery can be determined from the last menstrual period. Calculating childbirth by menstruation (determining the due date by the date of conception) is quite simple.

To calculate the gestational age and determine the date of delivery from it, you need to remember the day the last menstruation began. It is this date that is taken as the basis. From the date it is necessary to count exactly 3 months ago, add another 7 days to the resulting day. This will be the date when, most likely, there will be a beginning of a new life. If, for example, the last menstruation began on October 24, then you need to count back 3 months - it will be July 24, plus 7 days - it will be July 31. This is exactly the term of childbirth, calculated according to the last menstruation.

The duration of the menstrual cycle (MC) of a woman is important in determining the EDD. If the MC exceeds the usual 4 weeks, then the pregnancy lasts more than 40 weeks, and vice versa. But the error in this case is no more than 5 days.

Methods for determining EDD by ovulation

Due date calculation can be done in different ways. You can determine the date of birth not only by the last menstruation. It is easier to make a special weekly pregnancy calendar. But for this you need to know when fertilization occurred. And how to find out the date of conception?

First you need to remember how the process of fertilization proceeds. After menstruation, vesicles form in the ovary, in one of which a female cell appears. She breaks through the follicle and is released. Her path lies in the direction of the uterus. In this sexual path, under favorable circumstances, the spermatozoon fertilizes the egg. This is precisely the very favorable moment that you need to know in order to calculate the time of birth according to the day of conception. The fertilized egg continues to move towards the uterus, and its path can end only 7 days after meeting with the sperm. After that, there are changes in the structure of the mammary glands, the first signs of pregnancy appear.

Ovulation calendar calculation

If a woman does not know the exact day of ovulation, it can be determined based on her cycle readings. To calculate the date of birth by ovulation, you need to take into account several parameters:

• cycle duration over the past few months;
• systematic;
• duration and characteristics of menstruation.

Normally, menstrual cycles should be equal in duration, not have significant differences in start and end time, and in the nature of the course. If all these parameters are normal, then it will not be difficult to calculate the date of conception and draw up a labor schedule. The date of birth, calculated from the last menstruation, will be more or less accurate.

Irregular ovulation calculator

If the MC is not regular, then it will be more difficult to detect ovulation (and, accordingly, calculate the date of birth from the date of conception), but still possible. When calculating by the date of the last menstruation, the size of the error increases, since the result depends on the length of the cycle, which is always different. But in this case, it is also possible to calculate the date of birth by menstruation (according to the menstrual cycle).

Weekly pregnancy and child development calendar

Once the necessary calculations have been made, the woman is given a specific date when the birth can take place. There are many services that not only give an answer to the question “how to calculate the date of birth”, but also help to create a child development calendar. Such a weekly pregnancy calendar, in fact, allows a woman to draw up a specific action plan for the entire period of pregnancy.

Negele formula

Calculation of the due date is done according to the Naegele formula. To do this, a woman needs to know the exact day when the last menstruation before pregnancy began. Many women do not remember this day. Therefore, gynecologists recommend marking the first day of menstruation on the calendar to make it easier to calculate the date of birth by conception, especially if it was random.

In what week can delivery occur?

If you correctly calculate the approximate date of delivery, then you can make mistakes in specific days, but, as a rule, you can more or less accurately determine the week when the birth will occur. Due date "plus or minus a week" is calculated with higher accuracy.

Ultrasound determination of EDD

Ultrasound is now considered a reliable way to determine the date of delivery. If its results coincide with those calculated on the last monthly date of birth, then the probability of such a forecast will be higher than 90%.

Best time for ultrasound

To calculate the date of delivery by ultrasound, you need to contact the clinic. It must be remembered that the gestational age at which the examination is carried out is taken into account. If it is carried out at 11-14 weeks, then the error in determining the term of delivery will be 1-3 days. In the first trimester of development, embryos almost do not differ in size. In the second trimester, the weight and size of the fetus already have more significant differences, and in the third they become even more pronounced. Therefore, it becomes easier to find out the due date.

Meaning of accurate calculation of gestational age

Gestation is actually pregnancy. The difference between these two concepts lies in the fact that the gestation period is calculated as the number of full weeks of the entire period while a woman is carrying a child. The onset of gestation is counted from the calendar date of the start of the last menstrual cycle. Those. the concept of gestation makes it possible to more accurately calculate the approximate date of birth. The child is likely to be born at the time that the woman calculated based on the gestational age.

First stir method

You can calculate the date of delivery by the first movement of the baby during pregnancy. If you felt the baby move, how to calculate the estimated due date? Women during their first pregnancy feel fetal movement at the 20th week of pregnancy (that is, exactly at half the term). In the second and subsequent pregnancies, the first movement may occur at the 18th week. Accordingly, to calculate when the baby is born, you need to add 22 weeks. But it must be borne in mind that this method today is considered not the most reliable. But gynecologists, when they do weight measurements and other procedures, ask the woman and the day of the first stirring of the child.

Signs of close delivery

In the last weeks before childbirth, some signs begin to appear that may indicate the approach of childbirth. At this time, it is easier to calculate the day of childbirth, and the woman should be prepared for the fact that this will begin soon. With the help of a calculator, you can calculate how many days are approximately left until delivery. And then, by the date of birth, calculate the gestational age.

Features:

1. Belly goes down.
2. Appetite is constantly changing, the woman is losing weight. There is an upset stomach, the woman goes to the toilet very often.
3. The woman's mood swings are becoming more severe and more frequent. During this period, the expectant mother constantly wants to retire.
4. Shortness of breath and heartburn disappear. During most of her pregnancy, a woman feels that the fetus continues to press on the mother's internal organs. And before childbirth it disappears.
5. The baby in the stomach behaves much calmer and quieter.
6. Drawing pains appear below, in the pubic bone.
7. Mucous discharge from the vagina appears.

When does a woman start asking about the date of delivery?

When it's time to prepare a dowry for the baby or when it's time to go on maternity leave, to hand over everything to colleagues for a while, or maybe much earlier, when only the expectant mother wants to influence the fate of her baby by planning his birth under a certain zodiac sign?

One way or another, determining the possible date of birth is of interest to everyone. In anticipation of changes in the composition of the family, you need to plan the time of holidays, the family budget, you may have to turn to future grandmothers for help.

From a medical point of view, the date of delivery is important when planning a caesarean section or for those women who will be calmer and more comfortable waiting for the moment of delivery in a hospital.

EDD is an abbreviation for “estimated (planned) date of delivery”. It is worth paying attention to the fact that the date is precisely “estimated”.

No one can tell exactly when your child will decide to be born. But there are calculation formulas based on statistical data and the characteristics of female physiological cycles.

Many factors can affect the due date. Among them are the diseases of a woman, and the influence of ecology, and possible variations in the location of the placenta.

The emotional state of the expectant mother and her age are important. But in the case of a normal pregnancy in a healthy young woman, the discrepancy between the actual date of birth and the calculated due date will be small (3-5 days).

Determination of the EDD by the date of the last menstruation

The Naegele formula used for this calculation is based on the fact that a normal pregnancy lasts 10 lunar months (280 days). Therefore, if a woman kept a menstrual calendar and knows their exact date, you need to count back 3 months, and then add another 7 days to the result:

PDR \u003d Date of menstruation - 3 months + 7 days

that is, if menstruation was on February 10, then counting back 3 months we get November 10, and adding 7 days we find out the PDR - November 17.

Ovulation EDD calculation

If you were planning a pregnancy and the date of conception, then you probably followed. allows you to determine. Adding 38 weeks (268 days) to this day, we get the possible date of birth.

EDD = Ovulation date + 38 weeks.

How to calculate the due date from the date of conception

If a woman knows exactly the date of sexual intercourse that resulted in conception, another way to determine the date of birth can be offered. Physiologically, it is based on the same cycle as the basal temperature calculation, but does not require any preliminary measurements and charts.

EDD = date of conception + 266 days

That is, if sexual intercourse occurred on March 10, the expected date of delivery will be November 22. The error of this formula is 3-5 days, it is associated with the period of life of a spermatozoon in a woman's body.

Determination of PDR during a medical examination - the most accurate method

If a woman registers for an early pregnancy, then the condition and size of the uterus, the doctor will determine the duration of pregnancy and the approximate date of its completion (based on the "average" period of 40 weeks).

At a short term, the uterus is not yet palpable through the outer abdominal wall and a manual obstetric examination can tell about the term. But its characteristics are very subjective and depend on the qualifications of the doctor.

At 4 weeks, the uterus is the size of a hen's egg, by 8 weeks it will be larger - like a goose egg, and by 12 weeks will reach the edge of the pubic bone.

An experienced OB/GYN can determine the gestational age from these data.

Note that this technique works most accurately at the beginning of the first trimester. If a woman is not in a hurry for the first medical appointment, then there may be an error related to whether a large fetus is expected to appear, whether there is polyhydramnios, etc.

Planning the date of delivery based on ultrasound results

An ultrasound can accurately determine the size of the fetus and its maturity. This will allow you to guess the date of birth.

Moreover, if you go for examination in the first trimester and the gestational age is determined by the size of the ovum, then the doctor can give you other data when you repeat. This is not due to a mistake, just the intrauterine development of the baby is uneven.

The closer the due date, the more accurately you can determine the child's readiness for birth.

For example, to plan a hospitalization, preparation for a caesarean section.

Determination of the PDR by the date of the first movement

This method is less accurate than the previous ones, but is also physiologically justified.

All other formulas: calculation by the date of menstruation, ovulation or movement, are based on a standard 28-day cycle.

If a woman's menstrual cycle is less or more than 28 days, her physiological and metabolic processes may not fit into the calculated time frame. Moreover, there is not always a direct relationship here (that is, a woman who has a cycle of 25 days should not subtract 250 days from the date of the last menstruation instead of 280.

In any case, the calculation is carried out according to the standard formula. Just keep in mind that in your case, the likelihood of a baby being born a little earlier than the expected date increases).

The method with the greatest error - the calculation of the EDD by the date of the first movement - is further complicated by the fact that not every woman can accurately determine the moment of the first movement. The movements of the child are often mistaken for peristalsis or gases.

In addition to the objective calculation error, the date of birth can be affected by:

• chronic diseases of a woman;
• bad habits;
• heredity;
• or multiple pregnancy;
• mother's age;
• cold or bacterial infection already during pregnancy;
• repeated births;
• fetal pathology;
• stress.

As soon as she finds out about the pregnancy, the woman is already interested in the expected date of delivery. After all, by this moment you need to prepare a dowry for a newborn, if necessary, provide yourself with assistants or pick up a nanny for older children, plan a family budget, taking into account replenishment of the family and a long vacation for the mother.

Someone is in a hurry to improve their living conditions, make repairs or move closer to their relatives by the time the baby is born. And all these issues need to be resolved by a specific date, the DA.

Methods for calculating the date of birth were very relevant, calculation formulas were developed by obstetricians in different countries. With the advent of ultrasound, other methods with a large error began to be used less frequently. But they still arouse the interest of those who want to make a calculation without consulting a doctor, or at the stage of pregnancy planning.

The girl cannot become pregnant at any time. It is necessary to calculate as accurately as possible. If there are various problems with fertilization, then you need to follow a few simple rules that will help you get the desired result during the ovulation period.

Various . You can use free services on the Internet, which, based on internal algorithms, will be able to give out a favorable date for conception.

They all work on the same principle : you need to specify the date of the beginning of menstruation and indicate the duration of the cycle. However, this is only suitable for girls with a regular cycle.

There are other methods, namely:

• On its own from the moment of menstruation. It usually occurs 14 days after the onset of menstruation.
• Using the calendar, you can make a more accurate calculation, but you need to keep a monthly calendar. So, you need to find the duration of the longest and shortest cycles and subtract 18 and the shortest. The resulting figure will be the beginning of a favorable period. Subtract 11 from the longest period to find the end day of ovulation.
• If your cycle is irregular, you can determine the best period by measuring your basal body temperature. The thermometer should be held for at least 5 minutes in the mouth, vagina or anus. The measurement takes place in the morning from the first day of the cycle. During menstruation, the body temperature will be higher compared to the premenstrual period, and during the period of ovulation, it is maximum. The increase occurs up to 0.6 degrees.
• are sold in pharmacies and can also help determine the optimal time to conceive.
• Saliva analysis. It is necessary to apply biological material to the glass. If, after it dries, a pattern is formed that resembles a fern, then the girl is ovulating. The reason for the appearance of the picture is the increased content of salts in the body during this period.
• Ultrasound, which is the most accurate method for determining the favorable period for conception.

However, you can get pregnant not only during ovulation . There are also other periods in which having sex will lead to the birth of a baby.

What periods are favorable for conception?

Best practice. The probability of a favorable outcome is up to 90%.

There are also other periods when conception is possible, namely:

• Pre-ovulatory period. Spermatozoa in a woman's body live up to 7 days, so sex a couple of days before ovulation can lead to pregnancy. A few days before the onset of a favorable period, weak sperm have time to die on the way to the egg, while the strongest and healthiest remain. Thus, the likelihood of developing various fetal diseases during fetal development will be minimized.
• Postovulation period. Indeed, in a few days after the onset of ovulation, you can have a baby. The chances are quite high if there are no deviations.

There are even special techniques to determine the date of conception at the time of ovulation.

How to determine the due date?

It is quite difficult to determine the date of birth, as it is problematic to calculate the date of conception. But if a girl knows exactly when she ovulated and sexual intercourse with a man, then the calculation of the expected date of birth becomes much easier.

Ovulation

There are several ways to calculate the day of fertilization . One of them is the menstrual cycle. However, the result will have a rather high error, since the first day of the cycle is known, but there is no data on the last day.

Special . They are sold in pharmacies. With their help, you can find out the gestational age from the first days of fertilization. It is necessary to use it according to the principle of the usual test. In some models, the biological material is the blood of a potential mother.

Ultrasound is the most accurate examination. Here you can determine the period of fetal development with an error of 1-2 days.

Monthly

This is one of the most popular self-calculation methods. Here the girl knows the date of the beginning of menstruation and can count 280 days from the estimated date of conception. It is 280 days that an average pregnancy lasts.

At the same time, it is almost impossible to know the exact day of delivery. According to official statistics, the error up to 7 days is almost 85%.

Pregnancy 38-42 weeks is considered normal . If the baby is born before this period, then it is premature.

But different factors affect the duration , which include the hormonal background of the expectant mother, her psycho-emotional state, the presence of essential minerals and vitamins, and much more.

How can I find out the gender of my baby?

There are many different methods for determining the sex of a child. However, regardless of the method, there is a rather large error. Below are a few of these methods.

Ovulation

If you had sex a few days before ovulation then . The fact is that spermatozoa that carry the X chromosome are more tenacious. And the female body perceives seminal fluid as a foreign element. Therefore, the immune system begins to produce antibodies to destroy male germ cells.

The first to die are those that carry the Y chromosome. Sex a couple of days before ovulation with a probability of 70% can cause . But intimacy during or after ovulation is almost guaranteed to be a reason for joy for parents who are expecting a boy.

Frequency of intercourse

Research shows that abstaining from sex can result in a girl . But frequent sexual intercourse will cause the birth of a boy.

When a man does not have sex for a long time, his body begins to produce bodies that deactivate the spermatozoa with the Y chromosome. Sexual abstinence for 20-30 days is recommended to increase the chance of having a girl .

But a week of abstinence will lead to the conception of a boy , since during this period spermatozoa with the Y chromosome show maximum activity.

Blood renewal

The blood is constantly renewed. At the same time, the dominant trait of the parent with younger blood. Thus, if it was originally updated in a man, then the probability of having a boy is very high .

It is worth knowing the term for blood renewal. For men it is 4 years and for women 3 years . All accidental blood loss is also taken into account. To understand whose blood is younger, you can use mathematical calculations. It is necessary to divide the age of a man by 4, and women by 3. Whoever has a value less, of this gender, and you need to wait for a child.

Dieting

Nutrition of the future mother, according to some scientists, affects the development of a boy or a girl. The diet must be followed in advance, since sex is determined at the time of fertilization of the egg.

To give birth to a boy, you need to eat:

• large amounts of meat;
• flour products;
• legumes, mushrooms and potatoes;
• salty foods;
• oranges, peaches, bananas, cherries and apricots.

But for the birth of a female child, you need eat a lot of dairy food, fresh fish, various baked goods and drink tea or coffee.

Sex determination by date of birth

There is a table that allows you to guess the sex of the child by the estimated date of birth. However, here the error is quite high, since it is difficult to determine the exact date of birth. Various factors influence the duration of pregnancy. Therefore, it is not worth focusing on this method .

There are many other ways to determine the sex of a child. But the most effective is ultrasound . During it, the number of fruits and their gender will be visible.

Ultrasound

Ultrasound is performed several times during pregnancy to determine the presence of pregnancy, study the expected date of birth, identify the number of fetuses and various pathological diseases.

Ultrasound required three times during pregnancy, as different information is available to a specialist in different periods. At the same time, adjustments are made to the results of the previous study.

From the 4th conception it is possible to say when is the expected due date. According to the level of fetal development, a possible date of conception is determined, and it counts from it.

But this period is approximate, since the duration of pregnancy can be drastically reduced as a result of stressful situations and other factors that will negatively affect the hormonal and psycho-emotional background of a woman.

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