When Your Doctor Changes Your Pregnancy Due Date (2023)

FAQs

What does it mean when your doctor changes your due date? ›

“If dating is only based on the last menstrual period and a later ultrasound shows a discrepancy, then the due date may be changed,” Lamppa says. If your due date is confirmed by an ultrasound in the first trimester, it shouldn't change as the pregnancy progresses, even with additional ultrasounds, she says.

As pregnancy progresses, the accuracy of an ultrasound for predicting due dates decreases. Between 18 and 28 weeks of gestation, the margin of error increases to plus or minus two weeks. After 28 weeks, the ultrasound may be off by three weeks or more in predicting a due date.

It is very common when scanning an early pregnancy to find that the due date does not match the menstrual history. Sometimes the dates can be more than a week off and sometimes even as much as 4 weeks.

Even once your doctor has established a due date, there's no guarantee that your baby will come that day. In fact, only 6% of women deliver on their due date, Cackovic said. I tell patients that really, your due date is a date in the middle of almost a month-long period of time that you could have your baby.

Ultrasound-determined due dates are most accurate during the first trimester, and measuring 'ahead' doesn't result in a changed due date in most cases.

After the infant is born, there are a variety of characteristics that can be used to estimate the gestational age. It is possible for gestational age to be inaccurate by up to 2 weeks, even with an accurate LMP date confirmed by other tests.

You might find yourself being told that your due date is a different date than you originally expected. In fact, as many as 26% of people have their due dates changed in pregnancy.

You are more likely to be overdue if you are obese, have never given birth before or if you're over the age of 30. Your midwife or doctor will check that both you and your baby are healthy by giving you ultrasound scans and checking your baby's movement and heartbeat.

Between 22 0/7 weeks and 27 6/7 weeks of gestation, ultrasonography dating has an accuracy of ± 10–14 days 19.

To clarify, the gestational period of 40 weeks actually starts with the first day of your last period, which adds two weeks of time to the gestational period when your baby didn't even exist yet…

Can a due date be off by 6 weeks? ›

It typically lasts between 38 and 42 weeks. Then the doctor takes the average of those two time frames and adds it to the previous date and, voilà, your due date is determined. The problem is that this date can be wrong by up to 6 WEEKS!!! Your childbirth is not based on the average.

This is because the gestational age is calculated from the first day of your last menstrual period (lmp) and the fetal age is based on your baby's size as measured during a scan. It's normal for some difference between the gestational age and fetal age to exist, as babies develop in a normal range of shapes and sizes.

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.

Only about 5% of babies will arrive on their due date and focusing on this single date can make the end of pregnancy quite stressful. It may be more helpful to be prepared for you baby arrive some time after 37 weeks, and to focus on 42 weeks as the time by which you have a good chance of having given birth.

The results showed that in over 50% of cases the estimated date of delivery derived from the ultrasound scan was more accurate than that derived from the last menstrual period, whatever the discrepancy between the two predictions.

Measuring your fundal height is one way your healthcare provider can make sure the fetus's growth is on track. If you're told the fetus measures ahead or behind schedule, try not to worry. It usually just means an ultrasound or further testing is needed. The fetus is more than likely developing perfectly.

Your weeks of pregnancy are dated from the first day of your last period. This means that in the first 2 weeks or so, you are not actually pregnant – your body is preparing for ovulation (releasing an egg from one of your ovaries) as usual.

Most of the time, there's a harmless explanation. Maybe your due date is off by a few days or a week (it's pretty common for doctors to change due dates). Your baby could be in a funny position or sitting high in your uterus, and that's throwing the tape measure off.

Ultrasound is not very reliable for estimating fetal weight near term. For a 9-pound baby, an ultrasound's predictive accuracy is typically 15 to 20 percent off. Which means we may over- or underestimate by more than a pound.

If the measurement is low for the number of weeks, then the baby may be smaller than expected. Other tests used for diagnosis may include: Ultrasound to estimate the baby's size. Doppler flow to help check blood flow to the baby during pregnancy.

Can early ultrasounds be off by a week? ›

Ultrasound dating of conception is not reliable for determining paternity because the test can be off by at least 5-7 days in early pregnancy.

Most doctors and midwives are happy for you to go a few days over your due date as long as everything seems to be okay. Many will let pregnant women go up to two weeks over. After 42 weeks, however, the baby's health might be at risk.

After studying the data of various moms and their birth dates, researchers found a connection between high stress events and women having longer-than-expected pregnancies. Pregnant women that were 33-36 weeks along on September 11, 2001 were found to have more post-term pregnancies than expected.

Researchers found that babies born at late term—41 weeks' gestation—are slightly more likely to be classified as gifted and have higher standardized test scores than babies born at full term, or at 40 weeks' gestation.

The chance of delivering exactly on your magically assigned date is rare — only 5% of women will deliver on their Estimated Due Date. So there's a pretty good chance that your due date is wrong too. But why are we so bad at accurately predicting due dates?

Fetuses grow quickly, and they also follow the same pattern of growth in virtually every case. That means that by measuring the size of the fetus and looking for certain distinguishing characteristics, an ultrasound can give an accurate estimate of when you conceived.

When should I take my maternity leave? Some women begin taking their leave a week to a month before the expected birth because of discomfort or the desire for time to prepare. Others wait until the last moment so they can maximize their time with the baby once it arrives.

Between 41 weeks and 41 weeks and six days, a pregnancy is called late-term. When a pregnancy reaches 42 weeks and beyond, it's postterm. Late-term and postterm pregnancy can raise the risk of some health problems, including: Larger than average birth size (fetal macrosomia).

What happens if ultrasound does not match LMP? ›

LMP versus early ultrasound

If an ultrasound date in the first trimester differs from your LMP date by seven days or more, we would go with the ultrasound. If the ultrasound date is within seven days of your LMP date, we would stick with your LMP date.

Speak to your midwife or birthing care provider to understand what they based your due date on. Ask them if they took into account the length of your menstrual cycle and your ovulation cycle. Find out which due date calculation method they used.

First-trimester ultrasound (ultrasound before 13 weeks and 6/7 days) is the most accurate method to establish or confirm gestation age in pregnancy[1]. First-trimester ultrasound can be performed either trans-vaginally or trans-abdominally.

First babies are less likely to be “on time” at 39 weeks, and more likely to be a little late, between 41 and 43 weeks. Among full-term pregnancies, first babies are born about 1.3 days later on average.

More than 90% are born two weeks either side of the predicted date. But, as noted above, only 4% (or 4.4%, ignoring pregnancies with complications etc) are born on the predicted date itself - in other words, the chance of this happening is less than one in 20.

Ultrasound measurement of the embryo or fetus in the first trimester (up to and including 13 6/7 weeks of gestation) is the most accurate method to establish or confirm gestational age.

Your provider may recommend inducing labor if your health or your baby's health is at risk or if you're 2 weeks or more past your due date. For some women, inducing labor is the best way to keep mom and baby healthy. Inducing labor should be for medical reasons only.

An ultrasound is actually the most accurate way to date a pregnancy because all fetuses grow at a consistent rate during the first trimester and early second. In other words, if your baby measures 9 weeks 2 days when you have your ultrasound, that's how far along you are, no matter when your last period was.

This is because the gestational age is calculated from the first day of your last menstrual period (lmp) and the fetal age is based on your baby's size as measured during a scan. It's normal for some difference between the gestational age and fetal age to exist, as babies develop in a normal range of shapes and sizes.

Is it common for due dates to change? ›

You might find yourself being told that your due date is a different date than you originally expected. In fact, as many as 26% of people have their due dates changed in pregnancy.

It could be that your uterus size doesn't sync up with the standard growth charts (i.e. you measure big). And if the measurements are off by three weeks or more, in many cases your due date is moved to reflect this.

Can I wait for labor to begin naturally? Nature typically prepares the cervix for delivery in the most efficient, comfortable way. However, when there's concern about mother's or baby's health or the pregnancy continues two weeks past the due date, inducing labor might be the best option.

When a woman and her fetus are healthy, induction should not be done before 39 weeks. Babies born at or after 39 weeks have the best chance at healthy outcomes compared with babies born before 39 weeks. When the health of a woman or her fetus is at risk, induction before 39 weeks may be recommended.

"The risk to any individual baby born two to three weeks early is only about 4 percent, so we don't want parents to be alarmed," said study author Dr. Steven Morse, director of Community Newborn Services at the University of Florida.

A reverse due date calculator is helpful if you already know your due date and you want to find out when you got pregnant. To find out when you conceived, just subtract 266 days from your expected delivery date. You probably conceived around that day.

Your doctor will be making sure that you are healing as expected. By 6 weeks postpartum, your uterus should also have returned to its normal size – about the size of a grapefruit. If you are due for a pelvic exam, or if you had a complicated delivery or episiotomy, you can expect a pelvic exam.