When pregnancy lasts longer than 40 weeks

Many pregnant women are looking forward to giving birth by the time 40 weeks rolls around. That probably includes Kate Middleton, who is past her widely speculated due date of July 13. What happens when the baby decides to stay past 40 weeks? Rosanna Gray-Swain, MD, a BJC Medical Group OB/GYN who delivers babies at Barnes-Jewish Hospital, knows when babies should be induced and when nature should take its course. She shares her insight here.

What is the average length of gestation?
We consider 37-42 weeks a “full-term” pregnancy.Late delivery

What does going past the due date mean for mom and baby?
Going past your due date and going “post-term” are two different things. Women who deliver between 40-42 weeks are considered going past their due date. Post-term delivery is when a woman is pregnant longer than 42 weeks. About 7 percent of babies are post-term, and those babies have an increased risk for stillbirth, meconium (feces from the baby) passing into the amniotic fluid that can cause respiratory problems, or being bigger babies, which makes birthing more difficult.

Between 40-42 weeks, we will monitor the baby closely with non-stress testing and often ultrasounds to look at the fluid level around the baby to ensure the placenta can meet baby’s needs with oxygen and nutrition and there is adequate cushioning of the umbilical cord. Most often, OBs will induce patients by 41 weeks. If we try to induce before your due date, there’s a higher risk for a C-section. If a woman is induced after her due date, the risk for C-section is equal to those who go in to labor naturally.

Is there any risk to mom or baby to let nature take its course?
In general, if the amniotic fluid level and non-stress tests are normal, 40-42 weeks poses minimal increased risk to mom/baby under the supervision of a physician. If those are abnormal, there’s an increased risk for complications and delivery is usually indicated.

What can women do to speed up delivery if they are uncomfortable?
Taking laxatives is an old wives tale, and something we discourage because it can increase the risks associated with meconium and dehydration (from diarrhea).

We recommend a calm, peaceful environment. Intercourse and nipple stimulation may also increase the chances of going to labor. In addition, stripping membranes can be part of a cervical exam done by a provider at an office appointment. This massage of the cervix can help release natural hormones that are released during the beginning of labor and may promote the onset of natural labor in the next day or two.


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Category: Women & Infants

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Barnes-Jewish Hospital at Washington University Medical Center is the largest hospital in Missouri and the largest private employer in the St. Louis region. An affiliated teaching hospital of Washington University School of Medicine, Barnes-Jewish Hospital has a 1,800 member medical staff with many who are recognized as "Best Doctors in America." They are supported by residents, interns and fellows, in addition to nurses, technicians and other health-care professionals.

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