What Happens When Your Pregnancy Is Past the Due Date?

The risks and monitoring methods available when you are overdue

pregnant woman holding tablet

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Many pregnant women wonder what happens if their pregnancy goes past their due date, continuing beyond the expected 40 weeks or 280-day timeframe. There are some risks if your pregnancy goes well beyond the typical due date but there is actually a wider healthy range in pregnancy length than most people realize.

Full-term pregnancies typically last from 39 to 41 weeks but it is also not uncommon for a baby to come slightly before or after that timeframe. If fact, studies show that less than 5% of women deliver on their due date and only 70% give birth within 10 days of their due date. Additionally, most doctors do not consider a baby to be "late" until at least 41 weeks, and some give babies until 42 weeks before they intervene.

Delayed Deliveries

Doctors often refer to babies born past 40 weeks as "late-term" or "post-term," depending on how far past the full term date range your pregnancy goes. Babies born in certain time frames of pregnancy are categorized in the following ways:

  • “Early term” is from 37 weeks, 0 days to 38 weeks, 6 days
  • “Full-term” is from 39 weeks, 0 days to 40 weeks, 6 days
  • “Late-term” is from 41 weeks, 0 days to 41 weeks, 6 days
  • “Post-term” is from 42 weeks, 0 days or more

Some pregnancies do go post-term, in fact, according to the American College of Obstetricians and Gynecologists, 10% of all pregnancies go past forty-two weeks. However, some pregnancies categorized as "post-term" are actually the result of the incorrect assignment of a due date.

Due dates and the exact age of the fetus can be tricky to pinpoint because of many factors. Sometimes, this is because the woman's last period date is off or she had irregular periods. Ultrasound and other tests can only put a doctor in the ballpark.

Due dates are simply the doctor's best estimate of when your baby will come. 

Why Due Dates Fluctuate

Reasons for inexact due dates include irregular periods, miscalculated or inaccurate menstrual history, and mistaking spotting during very early pregnancy for a period. Doctors usually use several methods together to make their best estimate of a due date, including:

  • Calculation based on your last ovulation (the most reliable method)
  • Calculation based on the first day of your last menstrual period
  • Clinical examination of the uterus for size
  • Your first detection of fetal movement (the fetus usually makes its first movements felt by the mother between 16 and 20 weeks)
  • Fetal heartbeat (in normal pregnancies, the doctor can detect it between 18 and 20 weeks with a stethoscope and around 6 weeks using a vaginal ultrasound)
  • Ultrasound, which during early pregnancy can estimate fetal age within 7 to 10 days (it's not as effective later in the pregnancy)

Unfortunately, if you have irregular cycles, it could prove even more difficult to accurately predict a due date. In general, family history of long pregnancies (your own, your mother and sisters’ pregnancy histories, and your male partner’s family history) is the most important predictor of longer pregnancy duration.

Possible Interventions

Depending on your specific pregnancy, your doctor will determine if and when any interventions are needed to speed things along. In most routine pregnancies, your doctor will recommend letting nature take its course until you pass the due date by a week or so, as it's not uncommon for mothers to experience pregnancies longer than the allocated "full term" duration (as in going past 41 weeks). 

After 41 weeks of gestation, your doctor or midwife may have you do additional testing to ensure that you and your baby are healthy. This may include:

Based on the results of these tests you will either go home and wait for labor to begin on its own or you will discuss alternatives like induction or cesarean section. Induction is usually only indicated for medical conditions of the mother or baby that make staying pregnant riskier than waiting for labor to begin on its own.

Increased Risk of Complications

Recent studies have shown that there may be a greater risk of complications for both mother and baby associated with going post-term (42 weeks or more), including for the following:

  • Cesarean section
  • Higher neonatal intensive care unit admission rates
  • Infections and/or high blood pressure in the mother
  • Low fluid
  • Thicker meconium and/or ingestion of meconium by the baby
  • Use of forceps or vacuum assistance to extract the baby once in labor
  • Vaginal tears in the mother due to larger babies

Your doctor or midwife is the best resource on how these risks may or may not impact your pregnancy or be applicable to your situation. Consult with them about any concerns you may have about going past your due date.

A Word From Verywell

It can be stressful when your due date comes and goes without your baby's arrival. But rest assured that, in most cases, a longer pregnancy is perfectly healthy—and your baby will certainly come in the days ahead. Sometimes, interventions will be needed to get labor going but this is routine and safe as well.

The key is patience. Listen to your body and aim to enjoy your last few days before childbirth and the adventure of motherhood begins.

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