Last period before pregnancy calculator

Calculate your due date: How to find your baby's due date

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First day of my last period

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 their 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.

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Pregnancy Due Date Calculator – How Many Weeks Am I?

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Few things can compare to the rush and excitement of when you take a pregnancy test and read out the positive result! Once you’ve processed the news that you’re going to be a mom, your thoughts will naturally turn to planning and one of your first questions will no doubt be: when is my due date?

Use these three simple steps to find out how far along you are in your pregnancy:

1. Figure out when was the first day of your last period or the exact day you conceived.
   
2. Enter the relevant dates into the pregnancy week calculator.
3. Then hit Find out now! to find out how far along you are. 

Keep in mind every pregnancy is unique and the result will be an estimation rather than a fixed date.

While it’s true that most pregnancies last 40 weeks, there are other factors at play which will determine your due date. Most expectant mothers don’t realize that both menstrual and ovulation periods count as the first two weeks of pregnancy. Many won’t be aware of their pregnancy until their first missed period, and by that time they could be up to five weeks in. That means that simply estimating nine months from the day you take a pregnancy test isn’t going to calculate your due date, and, even so, factoring in a few weeks here and there for ovulation won’t either.

Unless you can pinpoint exactly what point of your ovulation cycle you were in at the time of fertilization, it’s difficult to know how far along you are and what date you’ll meet your baby. Luckily, our Due Date Calculator can help.

Using both the date of your last period and the length of your regular cycle, or exact date of conception, our Due Date Calculator will quickly work out your estimated due date, tailoring it accordingly for longer, shorter, and average cycle lengths.

Once you’ve calculated your due date, you can get a better idea of when to expect your little one – and start to plan accordingly.

If you haven’t done so already, one of the first steps you should take is to schedule an appointment with your doctor, who can confirm that you're pregnant with a blood test and physical exam, and also help you establish a more precise due date.

At each following prenatal care appointment, you'll be examined to determine the size of your uterus, and to monitor your little one's development. Pregnancy milestones such as hearing your baby’s first heartbeat and seeing your baby via ultrasound will be a thrilling part of these checkups. Along the way, depending on what is observed, your pregnancy due date may be adjusted.

While your doctor will be able to advise you best, there are still plenty of things you can do as soon as you discover you’re pregnant. Explore the rest of our site to find out more.

Gestational age. Date of birth. Calculate gestational age and due date

CONTENTS

1. What is a calculator?
2. How does the calculator work?
3. Other ways to determine and confirm the due date.
4. How accurate is the calculator?

What is a calculator?

In most cases, women do not know the exact date of conception, but they can with great certainty to say when the last menstrual cycle began. The first the day of the last menstruation is the starting point. Well, then 9 comes into play0003 pregnancy calculator - a program that makes a lot of calculations for you and answering almost all questions of interest to the expectant mother :

• when was the conception approximately;
• what is the estimated date of delivery;
• what is the exact week now and how much is left until the birth;
• how a child develops, what size it is, what it already does in the womb and what skills it has.

Calculator free, always available online, easy to use, has concise and understandable interface, will not let you make arithmetic errors and displays results in a visual and interesting way. In addition, you can always check the accuracy calculator, independently making calculations according to well-known obstetric techniques, which we present below.

To calculate the gestational age and expected date of delivery, a woman needs to enter in the calculator, only the date of the first day of the last menstruation (LPM) in the format "day month Year". If you enter the last day of your period or a known date conception, the calculator will show completely different results, you need to enter exactly the start date last menses.

The calculator calculates the obstetric period - this is when the first day of menstruation is considered like the first day of pregnancy. It is by obstetric term that gynecologists track the development fetus, prescribe tests and examinations.

The gestational age in the calculation results of the calculator is shown in weeks, this is the most simple and convenient interval. There are other generally accepted intervals for dividing such a large period - months (10 lunar months of 28 days) and trimesters. The trimesters divide the process intrauterine gestation into three phases of 13 weeks each.

The results display the exact time in weeks and days, a brief description of the development of the fetus, the height and weight for the calculated week are indicated, which organs are being formed, what can already be felt and do baby. A link is provided to the full article with colorful illustrations, telling about the condition of the fetus and mother, tests and examinations, recommended diet, possible problems and ways to overcome them. You will always know what to prepare for.

This calculation displays both fetal ages: the so-called "gestational" fetal age (menstrual), which is different from the so-called "ovulation" age (fertilization), it is two weeks less and is counted from the estimated date of conception. Therefore, all the details fetal development and well-being of women are considered from week to week, starting precisely from the third week.

In addition, you will know how many days are left before childbirth, under what sign of the zodiac and in what year of the Chinese calendar your baby will be born, by clicking on additional links you can determine the color of the eyes, the blood type of the child.

Depending on the week, additional links to calculators for checking ultrasound results are displayed, hCG hormone levels, blood test results, weight gain rates. If you wish, you can calculate an individual calendar of analyzes and examinations, both for mother and child.

Starting in the second or third trimester, you can find out about your benefits and calculate your benefits. amounts. For working mothers, it is possible to determine the date of maternity leave and find out if you are entitled to annual leave leave before the decree.

Whatever week you are, the calculator will offer you to test your knowledge using interactive tests "Care of a newborn", "Feeding of newborns", "Tests and examinations of pregnant women", "Rights of pregnant women". You will just have time to fill in the gaps and improve your knowledge on these important topics.

The calculator will also calculate the estimated date of conception of the child, by which, using Chinese gender calendar, you can find out who you will be - a girl or a boy. According to the results of the ultrasound, it will be interesting to know whether the prediction came true.

How does a calculator work?

All calculations of our calculator are based on the obstetric calculation method, as the most accurate, scientifically based and universally accepted method for calculating gestational age. other methods, for example, a report from the day of intercourse or from ovulation cannot be considered reliably accurate due to the characteristics of the reproductive system.

Cycle length may vary from woman to woman, one has 21 days, another has 34, moreover, in the same woman, the cycle may be irregular and fluctuate in duration during years for various reasons. On average, most women have a menstrual cycle is 28 days.

But one thing is common to all: conception of a child is possible only during ovulation - if there is no mature egg, then conception will not occur.

At the beginning of the cycle, a follicle forms on the surface of the ovary, inside which the female matures. sex cell. In the middle of the cycle, the follicle sac ruptures under the influence of strictly defined hormones. and allows spermatozoa access to the oocyte.

After ovulation, the female gamete lives from 24 to 36 hours, at which time conception must occur, otherwise the cell dies. This process is repeated every cycle.

It turns out, regardless of the length of the cycle, nature allocates only one or two days for the process of conception. However, this does not mean that sexual intercourse can lead to pregnancy only during the hours when the oocyte lives. Not, due to the ability of spermatozoa to survive for a long time in the female body, sex even 3-4 days before release the egg can lead to fertilization immediately after its release from the follicle. With active sexual life in general it is impossible to determine whether sexual intercourse before, during or after ovulation led to conception.

Therefore, in obstetric practice it is considered that conception occurs during the period of ovulation - 14 days before before the end of the menstrual cycle. And again, we are faced with a harsh reality here - a woman ovulates can happen both earlier and later than the above day. Based on all this, it is customary to count from the date of the last menstruation, this is both easier, and the woman usually remembers this date.

Thus, according to the obstetric standard, the first day of the last menstruation is the first day pregnancy, and the day of conception falls approximately at the end of the second week. If a woman finds out about the delay, then this is already the 4th week and the gynecologist, regarding a week-long delay, is already setting a deadline of 5 weeks.

Our online calculator is based on this obstetric method. Weeks are normal calendar months, and obstetric months, each of them has exactly 4 calendar weeks.

Pregnancy lasts an average of 40 weeks or 10 obstetric months well-known 9 months .