How To Know My Pregnancy Due Date

What If I Dont Know The Date Of My Last Menstrual Period

Pregnancy – How do I calculate my due date?

This is more common than youd think. Luckily, there are ways to figure out your due date when you cant remember the first day of your LMP:

  • If you know you had your LMP during a particular week, your doctor can estimate your due date accordingly.
  • If you have no idea when your last period was, your doctor may order an ultrasound to determine your due date.

Why Your Due Date Is Important

Your due date is likely one of the first bits of information youll seek out after you find out youre pregnant. Friends and family will want to know so they can look forward to greeting your new baby .

Doctors, midwives, and nurses will want to know so they can track important health milestones and make decisions about any potential interventions and prenatal testing.

Your due date is less of a deadline and more like a time marker. Your due date indicates the 40th week since your last menstrual period or the 38th week from ovulation.

Once your due date is calculated, you’re likely to give birth within a four-week period that surrounds your due date. In other words, sometime during the two weeks prior to and two weeks after your assigned due date, you’ll likely meet your baby.

Around 70 out of every 100 pregnant people will have their baby within 10 days of their due date. Assuming there are no complications, others will deliver either a little earlier or a little later than that.

The due date is valuable for many reasons, including the preparation of your home and family for the new arrival. There are also several other reasons it’s helpful to know your due date.

More Ways To Calculate Your Due Date If You Cant Remember Your Last Period

Another way is to guess the babys conception date. If the person knows the date of the sex that led to conception that would be another way to estimate it, but it could be off by several days as sperm can live for several days in the Fallopian tubes, says Strain.

Also, it’s possible to use fundal height measurement to guess the baby’s approximate stage of development. Fundal height is the distance from the top of the uterus to the pubic bone. At about halfway through the pregnancy, a fundal height measurement can be used to approximate the number of weeks a woman has been pregnant. A woman who is 29 weeks pregnant would have an expected fundal height measurement of around 29 centimeters, for example. The measurements may vary a little, but it’s still an interesting way to estimate the baby’s development, and from there the due date.


Christine Strain, a certified birth doula

Liza Maltz, postpartum doula

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How Do Home Pregnancy Tests Work

All home pregnancy tests measure the amount of a specific hormone known as human chorionic gonadotropin in your urine. When the embryo starts to implant in the lining of your uterus, as early as six days after conception, cells that will later develop into the placenta begin to produce hCG.

As the placenta grows, the amount of hCG in your body doubles every two days or so during the first few weeks. When hCG levels are high enough, the hormone enters the bloodstream. That’s when it starts to show up in the blood and urine. If the home pregnancy test detects enough hCG in your urine, it gives you a positive result.

Some tests are more sensitive than others. But in general, it’s easier for any home pregnancy test to pick up hCG in the urine when you’re 4 weeks pregnant versus 6 days after fertilization .

The best way to tell if a test is sensitive enough to pick up the smaller amounts is to read the fine print. Some urine pregnancy tests can detect lower levels of hCG. If you’re wanting to test early, before you miss a period, check the package insert to learn more about how much hCG needs to be present in your urine to detect a pregnancy.

First Day Of Last Period

Pregnancy Due Date Calculator Obstetric Wheel, Nurses, Midwifery ...

Most pregnancies last around 40 weeks , so typically the best way to estimate your due date is to count 40 weeks, or 280 days, from the first day of your last menstrual period . You could also subtract three months from the first day of your last period and add seven days.

The first day of your LMP is how most health care providers estimate a baby’s due date. But remember, it’s only an estimated due date, not a deadline for your baby to arrive. Just 4 percent of babies are born on their estimated due date.

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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 doesnt occur until day 14 of the menstrual cycle. So yes, you arent actually pregnant during those first two weeks of pregnancy.

Modern data suggests that women have their babies a few days after their due date on average. Studies like this one found that Naegeles 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.

Why Is It Important To Have An Accurate Due Date

It is important to have an accurate due date so that you and your chosen healthcare team can monitor your pregnancy appropriately and keep you and your baby safe. When you give birth to your baby it is important to know how far along you are in your pregnancy. Your doctors need to know whether your baby is being born early, on time or late.

If you go into labour early, it is important for your medical team to be prepared for various complications that can occur with prematurity. Your healthcare team may need to prepare to transfer your baby to a special care unit or NICU. If, on the other hand, you are overdue, your doctor or midwife may recommend you induce your labour to prevent complications that can occur with being overdue. This will be done in consultation with you, taking into consideration your birthing preferences.

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What Do I Need To Know About Using A Pregnancy Due Date Calculator

A due date calculator may not be completely accurate. This is especially true if you arent exactly sure when you had your last period, you have irregular periods or you dont know when you conceived. You should see your provider for a more precise test, such as an ultrasound, to confirm your due date.

Pregnancy Symptoms During Week 3

BEST Way to Calculate Your Pregnancy Due Date

No pregnancy symptoms?

Some women feel pregnant even before the test is positive, but most don’t notice anything yet. If you have symptoms this week, some of them may feel like PMS. Don’t worry if you don’t feel anything 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 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

Many women say that the tenderness they feel is an exaggerated version of how their breasts feel before a period. Some women also notice their nipples getting darker during pregnancy.


One in four or five women notice a small amount of spotting this week. This is known as implantation bleeding because it happens around the time the fertilized egg implants in the uterus.

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.

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Why Is It Risky For My Pregnancy To Go Past 41 Or 42 Weeks

Once you reach 41 weeks, the chances of your baby having problems starts to increase, and your caregiver will likely require you to come in for testing to make sure your baby is continuing to thrive in the womb. This is because the placenta is an organ that ages as the pregnancy progresses, and beyond 41 weeks it may not function as robustly in delivering oxygen and nutrients to your baby.

If your pregnancy goes past 40 weeks and 6 days, your provider may recommend that you have a nonstress test or biophysical profile. If the tests show that the baby is not thriving, your caregiver may decide to induce delivery.

If you don’t go into labor by 42 weeks, your caregiver will likely recommend inducing the labor. That’s because the risks for you and your baby increase significantly after that point. After 42 weeks:

  • Your baby may receive less oxygen and nutrients from you as your placenta starts to degrade or the amount of amniotic fluid decreases, compressing the umbilical cord.
  • Your baby may become too big for you to deliver vaginally.
  • There is a higher chance of stillbirth.

While you’re thinking about the big day, you might enjoy our video series on childbirth. We cover the signs and stages of labor, pain management, medical procedures, decisions about your newborn, and more.

Learn more:

March of Dimes. 2018. What is full term?

How To Know Your Pregnancy Due Date

December 19, 2017 by Team Babygogo

If youre pregnant and all excited about it, youd definitely be wondering when would it be that youll finally meet your little one.

Dont worry, you can actually know when its about to happen because calculating your due date is possible and not so tricky at all.

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Disclaimer About The Calculator

Our calculator strives for the highest accuracy, but your pregnancy progress may differ from the calculator’s results for several reasons including possible miscalculation errors in input data individual variations in the timing of ovulation, and/or conception.

The information provided regarding pregnancy progress and fetal development is a guide through the weeks. It is not specific information for a specific individual but serves as a general guide only. As each pregnancy differs, any dates, weights, and lengths should be considered general information for interest only.

Our week-by-week guides use both standard and metric units of measure including pounds and kilograms.

What If I Dont Remember The Date Of My Last Mensuration

Three Important Dates for Pregnancy

The due date calculation works best if your cycle is expected every 28 days and your periods are regular.

However, If you have an irregular menstrual cycle, you may not be sure about the date of your last period.

Meeting your Gynaecologist and taking his opinion, in this case, is essential. Your first ultrasound scan or a dating scan will be done to determine your due date which will give you a more accurate estimation.

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What Does It Mean If My Doctor Changes My Due Date

Your doctor may change your due date if your fetus is significantly smaller or larger than the average fetus at your particular stage of pregnancy.

Generally, your doctor orders an ultrasound to determine the gestational age of your baby when theres a history of irregular periods, when the date of your LMP is uncertain, or when conception occurred despite oral contraceptive use.

An ultrasound allows your doctor to measure the crown-rump length the length of the fetus from one end to the other.

During the first trimester, this measurement provides the most accurate estimation for the age of the baby. Your doctor may change your due date based on the ultrasound measurement.

This is most likely to occur in the first trimester, especially if the date estimated by the ultrasound differs by more than one week from the date estimated by your doctor based on your LMP.

In the second trimester, an ultrasound is less accurate and your doctor probably wont adjust your date unless the estimates vary by more than two weeks.

The third trimester is the least accurate time to date a pregnancy. Estimates based on an ultrasound can be off by as much as three weeks, so doctors rarely adjust dates during the third trimester.

However, its not uncommon for a doctor to perform an ultrasound in the third trimester if theyre thinking about changing your date.

Factors Affecting Due Date

With so much focus and excitement over an assigned day, youd think itd be an accurate numberbut its not always the case. The simple truth is that only 5 out of 100 people will deliver their babies on their actual due date.

Still, determining which week of pregnancy youre in is crucial to receiving good prenatal care and planning for your upcoming life change.

The majority of babies are born over a 35-day span, with birth typically occurring anywhere from about 37.5 weeks to 42.5 weeks. Due dates are also not deadlines. You could have your baby a week later than your due date and still be considered on time.

There are many factors that can influence your due date. First, each pregnant person has their own predetermined schedule.Many people will tell you that their pregnancies were all about the same length. If you had two kids, each delivered around 41 weeks, your third kid is likely to arrive around 41 weeks.

People who are pregnant for the first time tend to go into labor later. Youre more likely to go a few days past your due date with your first baby.

And finally, some people are at risk of preterm labor. About one in 10 pregnancies end with premature delivery. Maternal risk factors for premature babies include having a previous preterm birth, vaginal bleeding during pregnancy, diabetes, high blood pressure, smoking, and even periodontal disease.

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When Will My Baby Bump Show

This is one the most common things soon to be moms think about.

The answer to this question varies from pregnancy to pregnancy and mother to mother considering a few important factors.

  • If its your first pregnancy, you might show up a bit late due to tight abdominal muscles. You can expect a baby bump between 12 to 16 weeks.
  • If its not your first pregnancy, you can show sooner as your abdominal muscles are more lax since you have been pregnant before.
  • If you are thin, you can show earlier but if you are on the heavier side it might take a bit longer as a defined stomach or extra fat can hide the bump.

My Cycle Isnt 28 Days Will This Due Date Calculator Work For Me

How to Calculate Your Pregnancy Due Date? (Easy Methods)

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
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    Practical Example Of The Use Of Conception Date Calculator

    Let’s take Anne. She is 11 weeks pregnant and still doesn’t know her conception day. The first day of her last period was 11 June 2018, and typically, her cycle lasts for 31 days . As mentioned before, we can assume that her ovulation began around 17 days after her LMP, on 28 June 2018.

    11th June 2018 + 17 days = 28th June 2018

    She conceived around her ovulation date , on 28 June 2018. However, instead of all this counting, she used our pregnancy conception calculator.

    Next up is Maggie. She just came back from the doctor, who told her that the due date is on 19 September 2019. Now, she has one question: ‘what day did I conceive?’.

    19th September 2019 – 266 days = 26th January 2019

    You don’t have to do the calculations by hand! Just put the numbers into our conception date calculator based on the due date. It can also work as a pregnancy week calculator, giving you an estimated week of pregnancy and the first day of your last period.

    What Is The Ultrasound Date And Why Is It Different From My Due Date

    When a doctor performs an ultrasound, they write a report on the findings and include two estimated due dates. The first date is calculated using the date of the LMP. The second date is based on the ultrasound measurements. These dates are rarely the same.

    When your doctor evaluates the ultrasound results, theyll determine whether or not these dates are in agreement. Your doctor probably wont change your due date unless its significantly different from your ultrasound date.

    If you have more ultrasounds, each ultrasound report will contain a new due date based on the most recent measurements. An expected due date shouldnt be changed based on measurements from a second- or third-trimester ultrasound.

    Due date estimations are more accurate earlier in pregnancy. Later ultrasounds are helpful in determining whether the fetus is growing well but not for determining the age of the fetus.

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