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As you reach the end of your pregnancy, you may be feeling a mix of emotions about labor and delivery. Despite any worries about what lies ahead, you’re almost certainly ready for your pregnancy to end. After all this waiting, you want to meet your baby!
As your due date approaches (or even passes) if you haven’t gone into labor, you may be concerned. You might wonder if your baby is healthy, if your body is working properly, or feel like your pregnancy will ever end!
What does it mean to have an overdue baby? Are there medical risks associated with remaining pregnant past your due date? What should you expect to happen next after your due date passes?
Don’t worry, we’ve got you covered with the answers you’re seeking!
With all the different dates and terms you hear during pregnancy, it may be difficult to determine when you can expect to meet your baby! The American College of Obstetricians and Gynecologists (ACOG) uses the following definitions:
- early term: 37 through 38 weeks
- full term: 39 through 40 weeks
- late term: 41 through 42 weeks
- post term: beyond 42 weeks
Babies born before 37 weeks are considered premature and those born after 42 weeks are called postmature. (This can also be called a prolonged or overdue pregnancy.)
About 60 percent of women will give birth on or before their due date. Only about 1 in 10 babies is officially overdue or born beyond 42 weeks of pregnancy though.
Based on these statistics, you may be wondering how to calculate your due date and what factors might contribute to having an overdue baby.
The actual date of conception for a baby is hard to know, so gestational age is the most common way to calculate how far along a pregnancy is and predict your due date.
Gestational age is measured using the first day of your last menstrual period; 280 days (or 40 weeks) from this day is the average length for a pregnancy. This is your estimated due date, but the key word is “estimated,” since it’s nearly impossible to predict when a baby will actually be born!
The weeks surrounding your estimated due date are your due date window, and birth is likely to happen at any time during that period.
If you have no idea when your last period was, became pregnant while using oral contraceptives, or have extremely irregular menstrual cycles, your doctor will likely request an ultrasound to determine the gestational age of your baby. The ultrasound allows your doctor to measure the crown-rump length (CRL) or the distance from one end of the fetus to the other.
During your first trimester this CRL measurement can offer the most accurate estimation of the baby’s age, because all babies grow at roughly the same speed during that time.
However, during the second and third trimesters babies grow at different speeds, so this ability to accurately estimate age based on baby size diminishes.
Why is your baby deciding to take a little longer to be born? Some common reasons include:
- This is your first baby.
- You have a history of giving birth to post term babies.
- Your family has a history of giving birth to post term babies.
- You have obesity.
- Your baby is a boy.
- Your due date was incorrectly calculated.
When a labor extends beyond 41 weeks (late term) and beyond 42 weeks (post term) there are increased risks of certain health problems. Some of the most common risks associated with a post term baby are:
- fetal macrosomia, or being significantly larger than average at birth, which can also increase the risk of cesarean delivery or shoulder dystocia (getting a shoulder stuck behind the mother’s pelvic bone during delivery)
- postmaturity syndrome, characterized by baby not gaining weight past their due date, as well as dry or “loose” skin and long fingernails and toenails at birth
- low amniotic fluid, which can affect a baby’s heart rate and cause the umbilical cord to compress during contractions, resulting in a lack of oxygen flowing to the fetus
- meconium in the lungs of the baby, which can lead to serious respiratory problems
- stillbirth, when a baby dies before delivery
Late term and post term pregnancies can also involve delivery complications like:
- severe vaginal tears
- infection
- postpartum bleeding or hemorrhages
If your due date has come and gone, you can rest assured that you will continue to receive medical care. In fact, you’ll probably have more visits each week with your midwife or OB-GYN than you previously did!
At each of your appointments, you can expect that your doctor will check the size of your baby, monitor baby’s heart rate, check baby’s position, and ask about baby’s movement.
Your doctor may suggest some extra monitoring and medical tests to make sure that your baby is healthy. (Many doctors will begin to recommend this around 40 or 41 weeks.)
They’ll also ask you to be extra vigilant in performing kick counts, records of your baby’s movements.
Testing may occur once or twice a week and can include:
- Nonstress test (NST). This measures your baby’s heartbeat for a period of time (usually around 20 minutes).
- Contraction stress test (CST). This measures your baby’s heartbeat when the uterus is contracting to determine if there is fetal distress.
- Biophysical profile (BPP). This involves a combination of monitoring the fetal heart rate and an ultrasound exam. This combination of multiple tests allows the doctor to check the fetal heart rate, movement, and muscle tone. Amniotic fluid levels can also be assessed during the ultrasound.
- Cervical exam. This manual exam allows the doctor to determine the condition of your cervix. The cervix fully dilates and effaces during labor, so your doctor will look for signs of ripening and other changes that may indicate labor will begin soon.
Depending on the results of these procedures, your doctor may decide that it’s in the best interest of you and your baby to induce labor.
In making a determination to recommend induction, your doctor will take into account things like your age and health history, the health of the pregnancy, and the birthing wishes of the parents-to-be.
If your doctor or midwife would like to induce you, there are many things you can do to help nudge your little one along that range from more natural methods to medical procedures. Some methods of induction with varying effectiveness include:
You should have a discussion with your provider about which methods make sense in your particular situation.
Most babies are born within a few weeks of their due date. If you find yourself nearing the end of your estimated due date window with no signs of labor, there may be actions you can take to help nudge your baby into the world.
Before doing so, you should always consult with your doctor or midwife. They can discuss the benefits and risks of your specific health situation and offer guidance on the safest ways to help your little one arrive in your arms.
While it can be hard to wait, there are benefits to allowing your baby plenty of time to develop before entering the world. When the time comes that the risk of keeping your baby inside outweigh these benefits, your doctor or midwife will be there to support you in determining a safe birthing plan.
Your due date is just an estimate – in fact, only 5 percent of women actually give birth on that day. If your due date comes and goes and you're still pregnant, don't worry. Ob-gyns and midwives know exactly how to help with an overdue pregnancy.
I've gone past my due date – what happens now?
First of all, don't worry if you go past your due date, which is the day that you'll be exactly 40 weeks pregnant. Only 1 in 20 women will actually deliver on their real due date – most will have their baby somewhere between 37 and 42 weeks.
Your due date is calculated from the first day of your last menstrual period (LMP). Forty weeks – 280 days – from then is your due date. If you have an ultrasound in your first trimester, your healthcare provider will use it to confirm (or change) the due date that was originally determined based on your LMP.
Learn other ways to calculate your due date, based on your conception date or your IVF transfer date, for example.
Because not everyone has a regular menstrual cycle – with ovulation happening on the 14th day – it's easy for the LMP-based date to be off. Another reason the due date might not be correct is if you don't accurately recall your LMP (about half of women don't).
A term pregnancy is anywhere from 37 to 42 weeks of gestation. If your pregnancy lasts 41 to 42 weeks, it's called "late term;" one that lasts 42 weeks or longer is considered "postterm," or past due. In the U.S., 6.25 percent of pregnancies deliver at or after 41 weeks, and 0.33 percent deliver at or after 42 weeks.
If you're past your due date and still pregnant, it's understandable to feel anxious, uncomfortable, and tired of being pregnant. Try to be patient, and keep an eye out for signs of labor.
What will my doctor do if I go past my due date?
If you go past 41 weeks, your healthcare provider may recommend inducing labor. Or they may recommend weekly or twice-weekly visits and testing to make sure your baby is still thriving. These tests might include the following:
- A nonstress test (NST), which monitors the baby's heart rate.
- A biophysical profile, which monitors amniotic fluid and the baby's heart rate, breathing, movement, and muscle tone. This is an ultrasound but may also include an NST.
If there are pregnancy complications or if you reach 42 weeks, your doctor or midwife will schedule a time to induce labor.
What causes an overdue pregnancy?
Experts don't know what causes an overdue pregnancy, but genetics may play a role. They do know that having had a past-due baby before is a strong risk factor. The risk of a second past-due baby is increased two to fourfold.
Other things that delay labor might include:
- Carrying your first baby
- Carrying a boy
- Being obese
- Being an older mom (older than 40 years)
- Being of non-Hispanic white ethnicity
Are there any risks with an overdue pregnancy?
Most overdue pregnancies do just fine, with no complications for moms or their babies. An overdue baby may look a little different, though. Past-due babies can have relatively long and thin arms or legs, dry or peeling skin, and longer hair and nails than younger babies. They're often very alert at birth, too.
In some overdue pregnancies the following risks increase:
- Stillbirth. The risk is very low, but it does double (from 2 to 3 per 1,000 deliveries to 4 to 7 per 1,000 deliveries) after 42 weeks.
- Macrosomia. Because your baby has had more time to grow, they may become larger than average. This can make delivery more difficult and increase the risk of birth trauma (such as shoulder dystocia and injuries) for the baby. For you, a very large baby can increase the risk of perineal tearing, assisted vaginal delivery and/or cesarean delivery, and postpartum hemorrhage.
- Postmaturity syndrome, or dysmaturity. Because the placenta might not work as well this late in pregnancy, a baby can become malnourished, which puts them at risk for problems related to growth restriction and neurodevelopmental complications, such as seizures.
- Meconium in the baby's lungs. Meconium is your baby's first bowel movement, and it's more likely for them to have one in the amniotic fluid before birth if they're overdue. Inhaling some of it can cause breathing problems after birth.
- Oligohydramnios. When your pregnancy goes past term, the chance of having low amniotic fluid increases. This can restrict the flow of oxygen and nutrients to your baby as the umbilical cord is compressed.
How long can you go past your due date?
When to induce labor after your due date is something you'll want to discuss with your ob-gyn or midwife. Some practitioners recommend automatically inducing labor after 41 weeks, while others will monitor you for a week and induce at 42 weeks (or earlier if there are complications).
A labor induction basically means using drugs or physical methods to get your labor going. The method will depend somewhat on the condition of your cervix (whether it's begun softening, effacing, or dilating, for example). These might include:
- Amniotomy. Rupturing the amniotic sac (breaking your water) may help stimulate contractions and remove the buffer between your baby's head and your cervix, which may help your cervix dilate faster.
- Membrane stripping. Your practitioner will manually separate the amniotic sac from the uterine lining, which releases prostaglandins and may help start contractions.
- Oxytocin, a drug that will cause uterine contractions.
- Prostaglandin medication to start cervical ripening (softening your cervix in preparation for delivery). Prostaglandins sometimes help stimulate contractions, too.
- Foley catheter or cervical ripening balloon. A small device with a tiny balloon on the end is placed in your cervix. When the balloon is filled it puts pressure on your cervix and stimulates the release of prostaglandins, which in turn soften and open it.
Your baby will be monitored throughout the induction.
Wondering what you can do to get labor going on your own? Read more on natural ways to induce labor, including which methods are safe.
Learn more:
The stages of labor and delivery
Good sleep during pregnancy
Common pregnancy aches and pains