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Due Date Calculator — Amazingly Accurate Pregnancy Calculator

First day of your

Please choose the day your most recent period started.

Average cycle: 20 days21 days22 days23 days24 days25 days26 days27 days28 days29 days30 days31 days32 days33 days34 days35 days36 days37 days38 days39 days40 days41 days42 days43 days44 days45 days

or

Date you

Conception is approximately two days after intercourse.

Already know your due date? Click here

Pregnancy Week by Week Universal Header

Pregnancy due date calculator video

Learn how to calculator your pregnancy due date in this video.

When is my baby’s due date?

So you got your positive pregnancy test, you’re feeling some early signs of pregnancy, and now you’re wondering, “when is my baby’s due date?” We’ve got you covered with the Mama Natural due date calculator!

Enter your information in the due date calculator above and discover the best estimate for when your little bundle of joy will make his or her appearance.

How does this due date calculator work?

Because you may not know exactly when you ovulated or conceived, a due date calculator will typically calculate your estimated due date based on your last menstrual period (LMP).

Our online due date calculator uses a simple method to calculate your due date.

• Your due date is estimated to be 40 weeks after the first day of your LMP
• Your cycle is assumed to be 28 days long, with ovulation occurring at day 14
• Therefore the calculator adds 280 days (40 weeks) to your LMP

This method of due date calculation is known as Naegele’s rule (more info on this below).

Due date calculator quote Our standard due date calculator adds 280 days (40 weeks) to the date of your last menstrual period (LMP)

My cycle isn’t 28 days. Will this due date calculator work for me?

Yes. The logic behind our pregnancy calculator works as follows:

• The average cycle length is 28 days
• If your cycle length is shorter, your due date will be earlier
  • For every day your cycle is shorter, your due date moves one day earlier
• Similarly, if your cycle is longer, your due date will be later
  • For every day your cycle is longer, your due date moves one day later

What is the date of conception due date calculator illustration

How do you calculate due date from conception?

If you know when you conceived, our pregnancy calculator calculates your due date by adding 38 weeks to the date of conception. This method of calculation may be more accurate than a LMP due date calculation if you have irregular or consistently longer or shorter cycles than 28 days.

What exactly

The date of conception is the day that the egg and sperm meet.

Women who track their ovulation may know their exact date of conception. But for many women, date of conception can be tricky to pinpoint.

Sperm can live in a woman’s body for up to five days, and the ovum (egg) can live for up to 24 hours after being released. In other words, you have a six-day window where you could potentially get pregnant each month.

Do you already know your due date but want to know when you likely conceived? Try our reverse due date calculator.

What is an estimated due date (EDD)?

An estimated due date (EDD) is a “best guess” as to when baby might be born based on a due date calculator like this one.

However, only 4% of babies are born on their due date! Whereas 80% of babies are born within the window of two weeks before and two weeks after your due date calculator results. (See “due month” section below.)

Baby due date on a calendar with pregnant woman background – only 4% of babies are born on their due date

What is “gestational age?” Can it be different than what the calculator shows?

Gestational age (GA) is the term used to describe how far along the pregnancy is and how long baby has been gestating (growing in the uterus).

If you get an ultrasound you may notice a “GA” on the image with a number of weeks and days. This figure is based on how the baby is measuring, not on your LMP, which the due date calculator uses.

It’s normal for these dates to not match up perfectly. If there are significant differences in the dates, your doctor may want to dig deeper to determine conception date. As a result, your midwife or doctor may change your due date based on the ultrasound gestational age.

Early ultrasounds are very accurate when dating a pregnancy and can be helpful if you don’t know your LMP or your periods are irregular.

Note that you don’t have to have an early ultrasound, especially if you are fairly certain of your cycle length and conception window. This study shows that early dating ultrasounds don’t change the incidence of induction.

How are the weeks of pregnancy calculated?

The 40 weeks of pregnancy begin on the first day of your last menstrual period.

This can be a little confusing because, for most people, conception doesn’t occur until day 14 of the menstrual cycle. So yes, you aren’t actually pregnant during those first two weeks of pregnancy.

Here’s a more in-depth answer to that perennial question of How many weeks pregnant am I?

What is a

A “due month” is a more accurate timeframe for when you can expect to deliver your baby. Only 4% of babies are born on their due date. Whereas 80% of babies arrive either two weeks before the due date or two weeks after. Hence the term “due month.”

The length of a natural pregnancy can vary by as much as five weeks. (source)

A due month helps some mamas reduce the stress and fear of going past their due date.

To calculate your due month, simply subtract two weeks from your EDD given by your practitioner or our due date calculator and also add two weeks to your EDD. Voilà, your due month!

Yet another way to handle this tricky business of calculating your pregnancy calendar is to add two weeks to the end of your EDD and say, “Baby will be here before [that date].”

What is Naegele’s rule for due date calculation?

Naegele’s rule is what this due date calculator and pregnancy calendar is based on. Named after a German Obstetrician who practiced in the early 1800’s, Naegele’s rule predicts childbirth to occur 280 days after the first day of the last menstrual period.

However, Naegele’s rule assumes that your cycle is 28 days long with ovulation occurring on day 14, which isn’t the case for many women. So other ways of calculating your due date may be more accurate.

(How accurate is your due date? Find out in this post.)

Modern data suggests that women have their babies a few days after their due date on average. Studies like this one found that Naegele’s rule consistently places the due date about 2-4 days too early. So a better estimate may be 40 weeks and 3 days from LMP.

Alternatively, you can use our Advanced Due Date Calculator, which uses the Mittendorf-Williams rule to calculate your due date, which has been shown to be more accurate.

Due date calculator quote 2 Modern data suggests that Naegele’s rule places the due date about 2-4 days too early

What’s the Mittendorf-Williams rule?

This study done in 1990 showed that pregnancy lasted an average of 288 days past LMP for Caucasian first-time moms. For Caucasian women who were not first-time moms, their date of delivery averaged 283 days past LMP (3 days after Naegele’s rule predicted). This finding is known as the Mittendorf-Williams rule.

While Naegele’s rule is still the most widely used formula for a due date calculator, the Mittendorf-Williams rule is proving to be more accurate. But it’s a much more complex calculation, taking into account:

• Maternal age
• Race
• Height
• Weight
• Number of pregnancies
• Average luteal phase length
• Maternal education
• Alcohol during pregnancy
• Coffee during pregnancy

Our Advanced Due Date Calculator uses the Mittendorf-Williams rule.

Related Resources

• Our FREE Natural Pregnancy Week-By-Week Series ?
• My Bestselling Natural Pregnancy Guide ?
• Reverse Due Date Calculator ◀️
• Natural Birth Stories ??
• Baby Name Finder ?

Ready to calculate your due date?

First day of your

Please choose the day your most recent period started.

Average cycle: 20 days21 days22 days23 days24 days25 days26 days27 days28 days29 days30 days31 days32 days33 days34 days35 days36 days37 days38 days39 days40 days41 days42 days43 days44 days45 days

or

Date you

Conception is approximately two days after intercourse.

Already know your due date? Click here

How to correctly calculate the gestational age and determine the date of delivery

It often comes as a surprise to first-time pregnant women that in obstetrics the gestational age is determined not in months, but in weeks. But the surprises do not end there - the fact is that the obstetric period is calculated not from conception, but from the first day of the last menstruation.

In fact, pregnancy occurs two weeks after the start of the obstetric period, at the time of ovulation, when the sperm meets the egg. Thus, the age of the embryo, or gestational age, differs from the obstetric one by 2 weeks down. nine0003

How long does pregnancy last?

The obstetric term of a term pregnancy is 40 weeks, or 280 days. It is on the basis of the obstetric gestational age that the doctor will prescribe tests and examinations for you, determine the date of maternity leave and calculate the EDD (estimated date of birth).

Doctors use the Negele formula to calculate the EDD. According to this formula, if we add nine months and seven days to the first day of the last menstruation, we get the estimated date of delivery. nine0003

Unfortunately, determining the gestational age from the first day of the last menstrual period is not a very accurate method. It is well suited for women with a stable 28-day cycle, but if your cycle is slightly longer or shorter, then the date of ovulation shifts, respectively, and the actual obstetric gestational age will differ from the established one.

The most accurate way to calculate the EDD is to add 266 days to the date of the last ovulation (if you know it).

How to confirm pregnancy, determine the duration of pregnancy and the date of delivery nine0007

By itself, a delay in the start of a new menstrual cycle does not necessarily indicate pregnancy - failures can be explained by diseases, excessive physical exertion or stress. Pregnancy must be confirmed with an hCG test or examination on a gynecological chair. 1) Blood test for hCG cycle or the woman will feel the first symptoms. Also, an analysis of the level of hCG in the blood allows you to determine the gestational age with an accuracy of about two weeks. nine0003

2) Home pregnancy test

Home pregnancy tests also work by measuring hCG levels, but they are less sensitive than blood tests. The most modern of them can not only confirm the presence of pregnancy a few days before the delay, but also indicate (not too accurately) an approximate date.

Tests of the old generation will show a more or less accurate result only after a delay, that is, after 2-4 weeks from conception. nine0003

3) Gynecological examination

A qualified gynecologist-obstetrician can diagnose pregnancy during an examination starting 3-4 weeks after conception, focusing on changes in the shape and size of the uterus, as well as other signs.

4) Ultrasound

Ultrasound is the most accurate way to diagnose pregnancy. With the help of ultrasound with a transvaginal sensor, it is possible to determine the presence of a fetal egg in the uterus already 1-2 weeks after conception (3-4 obstetric weeks), but fetal heartbeats can only be detected for a period of 5-6 obstetric weeks. It is possible to determine the gestational age with high accuracy (up to 2-3 days!) With the help of ultrasound only from 6-7 weeks. nine0003

If the delay, as well as the result of an hCG test or blood test, indicate that you will soon become a mother, do not rush to get an ultrasound right away. Wait another 2-3 weeks, then by ultrasound you will not only be accurately determined by the period, but will also be allowed to listen to the baby's heartbeat.

If you did not do an early ultrasound to confirm pregnancy, then for the first time you will encounter this study at the 10-14th week. At the same time, the exact gestational age and PDR will be established or corrected for you. During pregnancy, you will need to undergo such an examination at least twice more. This will happen at 20-24 and 30-34 weeks. However, it is worth saying that ultrasound in the 2nd and 3rd trimesters may have an error in determining the gestational age. The PDR established according to them may differ from the real one by 2-3 weeks. That is why it is so important not to miss the first screening and do an ultrasound on time. nine0003

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〚 Pregnancy calculation. How to determine the date of birth? 〛Babystart official distributor

February 11, 2020

Most pregnancies last about 40 weeks (or 38 weeks from conception), so the best way to determine when due is usually 40 weeks or 280 days from the first day of your last menstrual 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. nine0003

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. nine0003

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. nine0003

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. nine0003

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.

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