The normal length of a pregnancy is 37-42 weeks. Five to ten percent of pregnancies spontaneously continue beyond 42 weeks, but we know that certain risks increase as we go past the “due date.” These risks include:

1.  Stillbirth (1/1300 after 41 weeks, 1/900 after 42 weeks)

2.  Increased cesarean deliveries for fetal distress as well as cephalopelvic disproportion (baby “too big to fit”).

3.  Postpartum hemorrhage

4.  Injuries to the baby during birth

We try to establish dating of the pregnancy early in prenatal care, so that we will not be worrying about patients going overdue at the end because of an error in the due date we have assigned, but nonetheless a significant number of women will not have delivered by 1 week after that date.

The two traditional options for managing pregnancies at that point are to wait for labor to start or to offer induction of labor (we give medicines to get labor started).   When we wait, we do some testing to try to predict who may be at risk for stillbirth: we use nonstress tests (monitoring the fetal heart rate) twice a week and ultrasound once a week to check the fluid around the baby, and if those things look good we are comfortable waiting until 42 weeks for labor to start. When the options of induction or watching and waiting have been compared, however, a number of studies have shown a lower cesarean section rate and probably a lower perinatal mortality rate (risk of the baby dying) if induction is routinely performed at 41 weeks instead of waiting.  One Canadian study showed a 24% risk of C/S and 2 stillbirths in a group of women managed with watch and wait, whereas there was a 21% risk of cesarean and no stillbirths in the women offered routine induction.  Two large meta-analyses (where they pull together many studies to get larger numbers of women) have confirmed this conclusion.  Neither of these reviews found an increase in complications from labor induction.

As a result of these recent articles, our policy at Full Circle was to offer induction at 41 weeks if other measures to induce labor have not been effective and it has not started on its own. We respected women’s and families’ choices to watch and wait from 41-42 weeks, if they preferred that, and were willing to monitor and continue to discuss options with patients who do not want to be induced.

“Natural” measures to induce labor

Nipple stimulation and making love – no good randomized trials, but the nipple stimulation increases Oxytocin levels and semen has prostaglandins and can serve as a cervical ripening agent.

Bowel irritants – castor oil has actually been studied for inducing labor. In the trial, it was effective in 57% of women who used it, but had significant side effects, including abdominal pain and diarrhea as well as increased meconium (baby pooping in the bag of waters while still inside). There was a trend towards increased fetal distress.[6] Another South African study also showed a correlation of castor oil use with increased passage of meconium.

“Sweeping membranes” – the midwife or doctor places a finger inside the cervix and sweeps it between the bag of waters and the cervix, separating these layers and stimulating prostaglandin release. One clinical trial showed that doing this daily for a week was as effective as using Cervidil, a prostaglandin suppository, to induce labor. A meta-analysis also showed a decreased need for medical inductions when this is done routinely, but noted that it is an uncomfortable procedure. [7]

Avoid Blue cohosh (caullophylum) – associated with fetal cerebral ischemia and cardiomyopathy in case reports.

Methods of induction: 

The medicines we use to induce labor are primarily

Prostaglandins for cervical “ripening”
Oxytocin to bring on contractions

If the cervix is not “ripe,” i.e. not already soft, shortened, and a little dilated, we recommend Cervidil for induction of labor. This is a small suppository we place in the vagina which ripens the cervix over a 12 hour period, and occasionally starts labor going. Another (and much cheaper) option is misoprostol – a pill is placed in the vagina. This is very effective but is associated with some increased risks.

A non-drug alternative with an “unripe cervix” is to use a foley catheter – this is passed through the cervix, the balloon is inflated, and traction is placed on the end of the catheter.  This works as well as the drugs above. 

If the cervix is ready to respond, we use pitocin intravenously, which stimulates strong and regular contractions.

 Risks of Induction:

In first-time moms at their due date, there was an 11.5% cesarean section rate if labor developed spontaneously, and 23.7% if labor was induced.   After 41 weeks, however, the C-section risk is higher with waiting.

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[4] Crowley P. Interventions for preventing or improving the outcome of delivery at or beyond term. Cochrane Database Syst Rev 2004;(3):CD000170.

[5] Sanchez-Ramos L, Olivier F, Delke I, Kaunitz AM. Labor induction versus expectant management for postterm pregnancies: a systematic review with meta-analysis. Obstet Gynecol 2003;101:1312-8.

[6] Altern Ther Health Med. 2000 Jan;6(1):77-9

[7] Cochrane Database Syst Rev. 2001;(2):CD000451.