# How Do You Count Pregnancy Weeks From The Start

## Calculate Using Your Last Menstrual Period

How to Count Weeks of Pregnant

The formula for calculating how far along you are is simply the number of days since the first day of your last menstrual period divided by seven:

Days since start of LMP ÷ 7 = # of weeks pregnant

Wondering how to calculate your number of months pregnant?

Days since start of LMP ÷ 30 = # of months pregnant

## How To Calculate How Many Weeks You Are

• Start by counting the recurring day of your last menstrual period
• Stop counting recurring days when you reach the present time.
• The number of recurring days you count is the number of weeks you are now.
• Example:count one week to the nextuntil you reach the present date.

LMP = December 2, 2022

1st Wed = December 9, 2022 = 1 Week2nd Wed = December 16, 2022 = 2 Weeks9th Wed = February 3, 2023 = 9 WeeksYou are 9 Weeks and 1 Day pregnant

Another method to calculate how many weeks pregnant you are is to:

• Count the days from the first day of your Last Menstrual Period until you reach today’s date.
• Now divide the counted days by 7.
• The answer will be how many weeks you are now.
• How Many Weeks Am I Formula:LMP = Last Menstrual PeriodHow Far Along Am I Formula:LMP = Last Menstrual Period*LMP date may be adjusted if unknown or following ultrasound.

Each of these methods will give you the gestational age of your pregnancy.

## How Accurate Are Due Dates

While due dates give you a good idea of when your baby may arrive, its unlikely your baby will be born on this exact date. In fact, only 4% of babies arrive on their due date1 most babies arrive within a week of their due date – around 90% of babies will arrive in the 2 weeks either before or after the predicted due date.

Also Check: What Is Safe To Take For Allergies While Pregnant

## Acog Definition Of Pregnancy

• Early-term: 37 weeks through 38 weeks and six days
• Full-term: 39 weeks through 40 weeks and six days
• Late-term: 41 weeks through 41 weeks and six days
• Post-term: any pregnancy that goes beyond 42 weeks

Sometimes, when talking about twins or triplets, you will hear people say things like, Twins are full-term at 37 weeks. But this isnt truly accurate. All pregnanciesincluding twins, triplets, or morearent truly full-term until they reach 39 weeks.

While you might be at greater risk of earlier labor with twins, that doesn’t affect how the timing of labor would be classified.

## Pregnancy Weeks Vs Months

Planning for a nine-month pregnancy can be confusing if you look at the total number of weeks in the average pregnancy. When you break down the numbers, it would seem that pregnancy lasts 10 months, not nine.

There are about 40 weeks in a full-term pregnancy. If you assume that a month is exactly four weeks long, that makes 10 months of pregnancy. The problem with this calculation is that it assumes that each month lasts 28 days. But most of our calendar months last 30 or 31 days.

To confuse matters even more, there is also the issue of when you actually became pregnant. While an exact date may not matter to everyone, you can estimate the date based on testing. By the time you have a positive pregnancy test, you are usually about four weeks pregnant.

The truth is that a full-term pregnancy lasts between nine and 10 months. To establish clarity about your stage of pregnancy and estimated due date, your practitioner will track your pregnancy in weeks rather than months.

Recommended Reading: How Many Days Pregnancy Test

## Calculate Using A Dating Ultrasound

A dating ultrasound, which measures the length of the fetus from crown to rump, is an accurate way to estimate your due date or how far along you are if completed within the first trimester . Most women have a pretty good idea of when their last period was, within a day or two, says Scurfield. If a woman has no idea, youll want to try to get her as early as you can. Once you get past 13 weeks, the variability of the growth is such that an ultrasound can be off by a week or so.

## When Should I Call My Physician Or Midwife

Your doctor may ask you to count your babys movements once every day. Count your babys movements to be sure that you feel at least 10 movements in 2 hours. If you think there is a decrease in your babys movements this is an important sign that your baby may not be well.

If you haven’t concentrated on counting the baby movements then it’s possible you may have missed them. Focus on the baby movements and count your baby’s movements, lie on your left side with support under your bump. Stay still for a couple of hours, during which time you should feel at least 10 separate movements.

You’re more likely to be aware of your baby’s movements when you’re lying down rather than sitting, and you’ll probably be least aware of them when you’re standing.

Here are some quick ways to encourage your baby to move:

If your baby starts to move around, all is probably well. But keep an eye on his movements from now on, and seek help sooner rather than later if you have any concerns.

You May Like: How Soon Can You Get Pregnant

## What Else Can The Weekly Pregnancy Calculator Work Out

As well as the specific week of your Pregnancy, the Pregnancy Weeks Calculator will also provide your approximate Due Date. The Pregnancy Weeks Calculator also provides detailed information about the types of changes that you will experience during the various weeks of your Pregnancy and the Development of your Baby.

## What If You Dont Know The Date Of Your Last Period Or Have Irregular Periods

Pregnancy Week By Week – Second Trimester

The due date calculation works best if the menstrual cycle is regular and the periods take place every 28 days. Just in case, one has an irregular menstrual cycle, then she might be unable to figure out her date of LMP. Or if her cycle differs in length, calculating from the first day of her LMP might not give us a date that we can trust. However, it can be really tough figuring out the date of the last period if the prospective mother has irregular period.

But the dating scan that is the first ultrasound of the prospective mother accurately tells us about the due date of the baby. The sonographer will carry out Crown Rump Length which will give an estimate idea of how far along is the pregnancy.

Also Check: When To Get Flu Shot During Pregnancy

## I Know My Lmp Do I Need A Dating Ultrasound

Nope! You can rely on the due date suggested by your last menstrual period, but your healthcare provider may schedule one anyway. Your doctor may do it for other reasons, but for figuring out dates, its really not necessary if she isnt concerned and theres nothing odd happening, says Scurfield.

## Fetal Kick Count And Movements

Most women feel the baby’s first movements after 18-20 weeks of the pregnancy. A baby or fetal kick count is among the most important observations to ensure the baby’s health. It is among the most important observations to ensure the baby’s health.

Check out our interactive baby kick count tool!

An active baby is usually a healthy baby and you usually feel your baby stretch, kick, roll and turn every day. Some babies are more active than others. All babies have periods of sleep during which they are not as active. You will get to know your babys pattern of movements and when your baby is most active.

Read Also: What Could Stop You From Getting Pregnant

## How To Calculate Your Pregnancy Due Date

Nothing is more exciting than when you finally see those double lines on the take home pregnancy test! While your mind starts swimming with who youre going to tell first, wondering where the baby will sleep, what you will name it and of course, all of the things youll need before, during and after babys arrival, one thing is indisputable your curiosity over how to calculate your pregnancy due date! While your doctor can help you answer this question, keep on reading for some ideas on how to calculate your due date!

## Dating Pregnancy Using Ultrasound

Ultrasound in the first trimester is the most accurate method of dating pregnancy. During the scan, baby is measured and the age of pregnancy is estimated by comparing baby’s size against recorded averages. If there is a significant difference between gestational age according to LMP and gestational age according to the ultrasound, you may be given a new gestational age and due date based on the ultrasound measurements.

Your pregnancy may also be dated by ultrasound measurement if an LMP formula was not appropriate for your pregnancy for any reason. LMP formulas are not suitable in several situations including the following: LMP is not known or is not certain, birth control pills were taken in the two months before LMP, the menstrual cycle is irregular, you are carrying multiples .

Although the age of pregnancy based on ultrasound measurements is more accurate than the age of pregnancy based on LMP, both are estimates and not definitive statements.

Read Also: What Can I Do For Acid Reflux While Pregnant

## What Is Naegele’s Rule

• Move the date back three months
• For example, if the first day of your last period was August 11, 2021, you would:

• Move the date back 3 months
• Your due date would be May 18, 2020.

If your fertility app gives you a different date than the one calculated by your doctor, it most likely because it was based on the ovulation date and not the date of your last period. If you ovulated earlier or later than day 14 of your cycle, this would shift your due date accordingly.

## Why Is 2 Weeks Pregnant Actually 4 Weeks

We cant count from the date of conception because its pretty hard to know for sure when conception took place. While we know that ovulation , this is by no means an exact science.

So the medical profession decided that to make things easier, it would be better to start the count from the 1st day of your LMP.

Don’t Miss: How To Avoid Nausea In Pregnancy

## How To Count Weeks Of Pregnancy

The first thing to know?

38 to 42 weeks is the average pregnancy span.

That being said, anomalies abound on either side of the spectrum. You can still have a perfectly healthy baby and a perfectly healthy mama if your pregnancy runs longer or shorter than average. Every pregnancy story is unique.

So when do you actually start the count? Warning: the answer may not be as intuitive as you think.

## How To Calculate Weeks Of Pregnancy

Self-Managed Abortion: How Many Weeks Pregnant Am I? | Episode 2

Pregnancy is calculated based on your last menstrual period. Week one of your pregnancy will start on the first day of your LMP. Likewise, the following weeks are calculated. This may sound weird, but it helps in giving the exact date for timely medical care. Unless you had an assisted conception and knew when the fertilization took place, the LMP method is the only way to know the closest ovulation and conception dates .

The doctors can help you with the exact calculation of weeks and months of pregnancy through other ways.

Also Check: Do Fertility Pills Work To Get Pregnant

## How Accurate Is The Due Date

The pregnancy calculator gives you an approximate due date, which it works out your due date by adding 280 days to the first day of your last menstrual period . Your period and ovulation are counted as the first two weeks of pregnancy. If you have the baby on your due date, your baby has been growing for 38 weeks, not 40, but you are still classed as 40 weeks pregnant.

## 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.

Also Check: How Do Girls Get Pregnant

## How Many Months Pregnant Are You

Rachel Gurevich is a fertility advocate, author, and recipient of The Hope Award for Achievement, from Resolve: The National Infertility Association. She is a professional member of the Association of Health Care Journalists and has been writing about womens health since 2001. Rachel uses her own experiences with infertility to write compassionate, practical, and supportive articles.

Women who are planning to have a child expect their pregnancy to last about nine months. But many expectant fathers and mothers wonder how many weeks there are in nine months. The average pregnancy lasts forty weeks from the first day of the last normal menstrual period.

To get a more specific prediction of pregnancy duration, most physicians and midwives use a gestation calculation like the one below to provide a personalized estimate. You can use the first date of your last period or the date of conception if you know it.

## Can You Calculate Conception Date

Whats interesting about predicting due date in pregnancy is that if the parents-to-be got pregnant the old-fashioned way, its easier to predict the due date based on the LMP. Conception typically occurs about 11-21 days after the first day of the last period.

However, in circumstances where pregnancy happened because of artificial insemination or invitro fertilization, conception date is fairly easy to determine as the exact date of conception likely involved a visit with your doctor.

Recommended Reading: What Happens If I Get Nexplanon While Pregnant

## Can I Plan My Due Date

Whether you’re trying to avoid being very pregnant in the middle of summer or are a teacher who wants to maximize time off with your little one, you can try to time when you conceive in order to “plan” your due date. But even if you’re one of the lucky ones who’s able to get pregnant when she really wants to, just remember that you probably won’t be able to map out exactly when you’ll give birth to the day .

Still, you can try our Ovulation Calculator, which uses the date of your last menstrual period and your typical cycle length to discover the days you’re most likely to be fertile and increase your chances of conceiving.

## How Do I Calculate My Due Date If I Had Ivf

If you used embryo cryopreservation and in vitro fertilization to get pregnant, you can use your IVF transfer date to calculate your due date. If your provider transferred the embryos five days after they retrieved your eggs, count ahead 261 days from the transfer date.

Don’t Miss: How To Help The Nausea During Pregnancy

## Will My Due Date Change When I Have A Scan

Youll get a more accurate due date once you have your dating scan. This is usually done at around 12 weeks of pregnancy, and will be used as the final due date given to you, especially if there is more than 5-7 days difference between your date based on your last period and the scan, or if your periods were irregular or you had just stopped hormonal contraception prior to getting pregnant as it is difficult to know when you ovulated exactly. It will not change however if you have had IVF treatment to conceive, as the exact date of conception is then known.

Ultrasound uses the size of the fetus to determine the gestational age . It is most accurate for dating purposes between 7 and 13 weeks of pregnancy. Earlier than 7 weeks and after 14 weeks, the measurements are not as precise in terms of calculating exact gestation.

## Literature On Reduced Fetal Movements And Outcomes

How to calculate weeks of pregnancy / Months of pregnancy / Probable date of birth

A recent study in The Lancet showed no reduction of stillbirth when women reported reduced fetal movements. However, the study did not mention how they defined “reduced fetal movements” making it difficult to interpret the findings. An editorial claimed that encouraging awareness of reduced fetal movements may be harmful. note that the advice to pregnant women in the study was that they should monitor changes in movements from 24 weeks and that they should refer themselves immediately if they detected altered movement after 28 weeks. The editorialists observed, With hindsight, the recommendation to encourage mothers to report changes from as early as 28 weeks might have been misguided. They added, Although overall deaths were not stratified by duration of gestation, it is plausible that limiting awareness campaigns to beyond 37 weeks would be safer.

Yaffe HDaily fetal movement recording and fetal prognosis.Obstet Gynecol. 1973 41: 845-850

Heazell AEPLi Met al.Alterations in maternally perceived fetal movement and their association with late stillbirth: findings from the Midland and North of England stillbirth case-control study.BMJ Open. 2018 8: e020031

Stacey T

Recommended Reading: How To Figure Out How Far Pregnant I Am