What Is A Pregnancy Due Date And How Do Doctors Calculate Them
Your pregnancy due date is an estimation of when your unborn baby will arrive, based on when they were conceived. If you know the exact datewhich will most likely be the case when you’ve used in vitro fertizilation or interuterine inseminationit will make the estimate more accurate. However, even knowing an approximate date is helpful.
From What They Are To How Doctors Calculate Them Read On To Learn More About Pregnancy Due Datesand How You Can Estimate Yours At Home
You’ve taken a blood test or an at-home pregnancy test. Two little lines have appeared, and you know you are expecting. You have a “bun” in your proverbial oven. But when will your little one arrive? Well, no one knowsat least not for sure. Pregnancy due dates are estimates, ones which are rarely accurate. Only 5 in 100 people give birth on their due date. Still, they are an important part of pregnancy, as due dates will help you and your doctor best prepare for your little ones arrival.
Here’s everything you need to know about due dates, from what they are and how they are calculated to how you can best estimate your baby’s arrival at home.
How To Calculate How Many Weeks You Are
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:
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.
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How Far Along Am I
enterdue datelast period
The How Far Along Am I Calculator uses your due date or last menstrual period to calculate how many weeks, months, and days you are pregnant.
different starting dates to count pregnancy
- Conception or ovulation
- Measurements from an ultrasound
- IVF Transfer date
Pregnancy is most commonly measured gestationally from a woman’s last menstrual period to birth. This period is known as gestational aging.
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.
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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.
Weeks 7 Days Pregnant
Once you reach 39 weeks pregnant, you can celebrate that your baby has reached full-term! You have worked hard to get here, so find a simple way to celebrate this milestone. Go to the spa or salon, enjoy a special meal with friends or family or just take a moment to appreciate how far you and your baby have come.
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Role Of Fundal Height
Your midwife or doctor may measure your fundal height at your pregnancy well-checks. The fundal height is the measurement in centimeters from your pubic bone to the top of your uterus. It should grow at a predictable rate as your pregnancy continues.
After 20 weeks, your fundal height in centimeters will typically be the same as the number of weeks you are pregnant. In other words, at 21 weeks pregnant, your fundal height should be around 21 centimeters .
Sometimes, the fundal height won’t match perfectly. Slight variations are normal, but if you are measuring much smaller or larger than expected, your medical care provider may want to investigate with another ultrasound.
While useful, the fundal height is not an accurate measurement of gestational age and would not affect the estimated due date.
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.
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 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?
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Pregnancy Week 36 Fetal Development
Your babys skull is made up of relatively soft and flexible bones. This will allow him or her to go through the birth canal during delivery. Theyll eventually harden during the babys infant years.
Theyll be shedding most of their lanugo, which is the soft downy hair that covered their body. These tiny hairs will mix in with the amniotic fluid. Inside their bowels, their first stool is forming. This is called meconium. Its sterile and your baby wont release it until after birth unless theres any sort of fetal distress.
Pregnancy Week 38 Fetal Development
Your babys brain, lungs, and liver continue to grow in the final weeks of pregnancy, which is one of the reasons why its important to deliver at full term, or as close to full term as possible.
The lanugo will be gone or nearly gone by now.
Your babys bowels will also be storing its first poo, called meconium, which it will pass after delivery. Meconium is a slimy substance that is made up of anything your baby may have swallowed in the uterus.
I Just Took A Positive Pregnancy Test: How Many Weeks Pregnant Am I
Home pregnancy tests measure hCG in your urine, which starts being produced right after implantation. However, it takes a few days for it to accumulate enough in your urine to be detectable. Home pregnancy tests wont show a positive pregnancy until youre at least 5 to 6 days away from the expected date of your next period. At this point, youre already more than three weeks pregnant. If you took the test on the date of your expected period, youre considered four weeks pregnant .
How To Calculate Ivf Due Date
If you underwent in vitro fertilization, you have the benefit of knowing exactly when the egg was fertilized, so an IVF due date calculator can be very precise. Plus, you dont have to worry about any changes to babys anticipated date of arrival as you might with a pregnancy calculator based on LMP. Your baby due date is determined by either when you ovulatemeaning your egg retrieval or intrauterine insemination dayor whether youre having a three- or five-day embryo transfer. For a day three embryo, count forward 263 days from the transfer for your due date for a day five embryo, add 261 days. If youre undergoing IUI, your due date is 266 days later.
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Where Does 40 Weeks Come From
The most common way to calculate a due date is to set it at 40 weeks past the woman’s last menstrual period. This is known as Naegele’s Rule, after the German Obstetrician Franz Karl Naegele who published the method in 1806. He suggested taking the first day of the expectant mother’s last period, adding one year, subtracting three months, and adding seven days, although the science behind what he said isnt clear.
It is important to remember that your due date is not set in stone, but is in fact an estimate of when you might go into labour give or take 2 weeks!
Read The Instructions Completely
Sure, youve done this before, and you totally get the gist of it. Pee on the stick, wait a minute, and voila! Magical answers!
Hold your horses there. Some pregnancy tests may have a variation or unique features to watch. For example, with most tests, you shouldnt tilt the front upwards as you pee, or even after, because that could mess up the results.
Reading the instructions carefully will help you to do the test They also often tell you how early the test can be taken, how long to wait before trusting your result, and other important factors.
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How Can I Calculate Important Week
This pregnancy calculator helps you find out exactly how many weeks pregnant you are right now, details your baby’s development, and precisely what is happening to your body at the moment. Just enter your pregnancy due date or other information to create and calculate a personalized weekly and daily pregnancy calendar. The babyMed Monthly Pregnancy Calculator and Calendar is a week-by-week pregnancy calculator and calendar with information for each day of your pregnancy.
How Long Are Women Actually Pregnant For
A study from 1990 of over 1000 women found that the median gestation length for first-time mothers was 277 288 days since LMP. For second-time mothers, median gestation length was slightly shorter and about 275 287 days since LMP.
Interestingly, one study of a small population of 125 Caucasian women found that gestation lasted on average 268 days from ovulation, and that despite no labor or preterm complications in the sample pool, gestation length varied by 37 days across the sample. Progesterone may explain the variability because a slower rise in progesterone after implantation correlated with a longer pregnancy. But, keep in mind, this is a small sample size with one racial background.
Although research doesnt understand why yet, racial background does affect gestation length. A study of over 100,000 women in London found that women of African or Asian backgrounds had a median gestation length of 273 days, which is about a week shorter than Caucasian women.
Bottom line: how many weeks pregnant the average woman is when she gives birth does vary considerably, but about 282 days from LMP seems to be more accurate although whether thats true for women of all ethnic backgrounds definitely requires more research.
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Your Common Symptoms This Week
You cant attribute any symptoms you feel during week 1 to pregnancy just yet. This weeks discomforts are brought to you by menstruation.
As such, you might be feeling the way you usually do during your period. Some women dont have many menstrual symptoms at all, but for others, fluctuating hormones can lead to typical issues such as:
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Sex At Week 36 Of Pregnancy
It could be getting uncomfortable by now, but sex is still perfectly safe. In fact, you can keep on having sex right up until your due date. Try different positions to see what works for you! And if youre not in the mood for sex, there are other ways to spend quality romantic time with your partner.
When youre 36 weeks pregnant, its normal to feel like theres so much left to do! Here are some things you can try scheduling for this week:
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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 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.
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.
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How To Calculate The Estimated Due Date
To calculate the probable due date, which should be around 40 weeks after your LMD, add 7 days to your LMD, and then count 3 months back and add one year.
For example, if the LMD was March 11, 2021, add 7 days, , then subtract 3 months and add 1 year . In this case, the estimated due date is December 18, 2018.
This calculation is not because the baby can be born between 37 and 42 weeks of pregnancy, however, it allows the parents and health care team to prepare for delivery.
First Day Of Last Period
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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When Should I Call My Doctor
A note from Cleveland Clinic
A due date calculator helps you plan for your babys arrival. Keep in mind that a due date calculator is only an estimate. Youll need to see your provider to confirm the date. Your due date may change when you have a prenatal ultrasound. Your provider may even change your due date more than once during your pregnancy, but it usually only changes by a few days. Knowing when to expect your new family member allows you to prepare mentally and physically. An accurate due date also helps your provider monitor your health and the health of your baby.
Last reviewed by a Cleveland Clinic medical professional on 10/07/2021.
Why Is The Ultrasound Method So Useful In Calculating How Many Weeks Pregnant You Are
Healthy embryos grow at a very predictable rate in the first trimester, so the crown to rump measurement can provide a more accurate estimate as to how many weeks pregnant you are. Crown to rump refers to the distance between the head to the end of babys bottom . When dating ultrasounds are done before the 13th week of pregnancy, their accuracy is +/- five to seven days. In the second trimester that jumps up to +/- seven to 10 days.
The above image depicts an early ultrasound used for dating purposes.
If you get an official due date from your dating ultrasound, you can use our reverse due date calculator to see when you likely conceived, then youll have a much better answer forhow many weeks pregnant am I.
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Pregnancy Week 37 Fetal Development
At this point, baby is too big to do much kicking and punching. Youre more likely to feel her stretching, rolling, twisting, and turning as it gets more crowded in there. Your uterine wall continues to stretch out, becoming thinner and letting more light through as baby starts to adjust to a more regular schedule.
Currently, baby is practicing breathing by inhaling and exhaling amniotic fluid. The brain and lungs arent quite finished growing and developing, although if baby is born this week, everything is likely to be just fine.