Conception and due date calendar

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:

Figure out when was the first day of your last period or the exact day you conceived.
Enter the relevant dates into the pregnancy week calculator.
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.

How to calculate the due date. Calculate gestational age by week

Our online pregnancy calculator will help you calculate gestational age by week and find out when your baby will be born

Last period start date

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Determine the date of birth

It is impossible to calculate the date of birth with absolute accuracy. The estimated day of delivery is calculated as follows: the first day of the last menstrual period + 280 days . This is an average date, usually delivery occurs in the next plus or minus 10 days . Learn more about the calculation of the PDR.

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How to calculate due date

What is PDD?

EDD is an abbreviation commonly used by physicians for the phrase "estimated due date".

How is the estimated due date (ED)

How to correctly calculate the due date? Pregnancy from conception to the birth of a child lasts about 266 days, or 38 weeks. Since the date of conception, as a rule, is not exactly known, in modern obstetrics it is customary to calculate the gestational age from the first day of the last menstruation, i.e. you need to calculate the date of birth by menstruation. With this calculation, it is approximately 280 days, or 40 weeks, since ovulation and, accordingly, fertilization usually occur two weeks after the start of the cycle. Ultrasound equipment is also set up for the same calculation of the gestational age, therefore, if menstruation is delayed by 4 weeks, the doctor will most likely report 8 weeks of pregnancy (whereas only about 6 weeks have passed from the moment of conception).

Accuracy of due date calculation

How to calculate exact gestational age? You can calculate the approximate date of birth of a child if you know the date of the last menstrual period. The estimated due date (EDD) will be 280 days (40 weeks) after the first day of your last period. However, only 5% of children with normal pregnancies are born on the “calculated” day, another 85% are born within a period of plus or minus a week from this date, and another 10% are “late” or “hurry” for another week. It is believed that a healthy pregnancy can last from 38 to 42 weeks.

Duration of pregnancy

How to correctly calculate the duration of pregnancy? The duration of pregnancy depends on many factors, including the individual pace of development of the child, as well as the duration of the woman's menstrual cycle. So, for example, if the cycle duration is less than 24 days, then childbirth can occur 10-15 days earlier than when calculated according to the formula "1st day of the last menstruation + 280 days", while the child will be fully mature and healthy. And if the menstrual cycle lasts more than 32 days, then the pregnancy can drag on for 10-15 days, and this will not be considered overdose.

The calculator was developed in accordance with the recommendations of Ph.D. obstetrician-gynecologist Tatyana Solomatina, author of the book "Advice to those who have flown."

Pregnancy Calendar - Perinatal Health Center

Whether it's your first pregnancy or you already have a baby and are expecting another one, it's an exciting time in your life. You began to feel the birth and development of a new life within yourself.

Due date calculation

In most cases, women do not know the exact date of conception, but they can tell exactly when the last menstrual cycle began. This is the point from which pregnancy is usually counted. For most women, the most likely period of fertilization (ovulation) lies in the middle of their monthly cycle, in other words, two weeks before the start of the next menstrual cycle.

Based on this date, the pregnancy lasts about 280 days, or 40 weeks, from the start of the last menstrual period. So you can get your estimated due date by adding 280 days to the date you started bleeding in your last cycle. The same result can be obtained by adding 7 days to the date of the last menstrual period and subtracting 3 months. For example, if your last period started on February 20, then your due date is expected to be November 27.

This calculation of pregnancy determines the so-called gestational, or menstrual, age of the fetus. It is on this “calendar” that doctors and nurses will track the development of the fetus. Gestational age is different from ovulation, or fertilization, age, which is two weeks earlier and is counted from the actual date of conception.

Many people calculate their pregnancy in weeks. This is the easiest and most convenient way to avoid confusion. For example, if your doctor says that you are 10 weeks pregnant (remember that the count is from the start of your last menstrual period), then you conceived about 8 weeks ago and will go into labor in 30 weeks because your total pregnancy is 40 weeks.

There is also a large unit of measurement - trimester. The trimesters divide the pregnancy into three phases. Each such phase, lasting 13 weeks, has its own characteristics.

You may also have heard of another unit of time, the lunar month. It corresponds to the cycle of lunar phases and is 28 days. The full gestation period, equal to 280 days, is 10 lunar months.

The calendar is based on a 42-week pregnancy schedule. The expected time of labor (ETD) is at the end of the 40th week. This way you will know the age of the developing fetus at any point during the pregnancy.

It is important to understand that the RID is an estimate, not a precise date. Only one woman in 20 gives birth on the exact day0 percent of women give birth a week earlier or a week later. Therefore, one cannot rely on the date of the OVR. It may turn out that it will come, and the child will not be born for some time. Consider this date as a guideline - a deadline for which you must prepare.

There is no fundamental difference how to count the time of pregnancy. Still, the process will not go faster. It will continue as long as nature allotted. After all, a miracle happens - a new life grows and develops in your body!

Your menstrual cycle

You estimate that your menstrual cycle probably ends at the beginning of the second week of pregnancy or a few days earlier. The usual interval between periods is 28 days, but they can occur after 21 and even after 35 days , and there is nothing abnormal in this. Actually menstruation in most cases lasts from 4 to 6 days. Discharge from the uterus is a mixture of sloughed uterine mucosa and blood. Clotted blood clots may also appear. On average, during menstruation, a woman loses 25-60 ml of blood. Blood loss can be different for different women, and for one woman it can change from one cycle to another.

Two important biological cycles occur almost simultaneously in a woman's body. As a result of the ovulation cycle (ovulation), a mature egg appears, ready for fertilization, and during the endometrial cycle, the uterine wall is prepared for implantation of the fertilized cell. Both cycles are closely related to each other because endometrial changes are regulated by hormones that are released in the ovary.

The normal alternation of the ovulation and menstrual cycles (with the production of one egg for fertilization) is the rule, not the exception. Some women experience uneven cycles of egg production. Such cycles can take place without ovulation. This is quite rare compared to regular and predictable menstrual cycles and hormonal changes.

Your body produces many hormones, including follicle stimulating hormone (FSH) and luteinizing hormone (LH) produced by the pituitary gland, as well as estrogen, progesterone and androgens (testosterone) produced by the ovary.

The natural purpose of the ovulation cycle is to produce an egg for fertilization. The body of a newly born girl contains about 2 million eggs. Their number is reduced to about 400 thousand by the beginning of puberty. But the maximum number of eggs is formed even before birth.