How Long Should Pregnancies Last? Experts Reach 39-Week Consensus; Recommend Induction

ACOG (the American Congress of Obstetricians and Gynecologists) revised its position on the optimal length of pregnancy for low-risk pregnancies. Yesterday, there was a debate at the 2016 Annual Clinical Meeting that turned into a statement of consensus: waiting to have a baby after 39 weeks’ gestation is not a good idea.

This consensus comes as more evidence has been rolling in regarding the relative risks of waiting for a ‘natural birth’ as opposed to induction. According to Errol Raymond Norwitz (MD, Ph.D., chair of the Department of Obstetrics and Gynecology at the Tufts University School of Medicine in Boston), “Continuing the pregnancy beyond 39 weeks is riskier than previously believed for the fetus.

Dr. Charles Lockwood (dean of the Morsani College of Medicine at the University of South Florida) describes his change in perspective on the matter. He states that he “…was absolutely opposed” to the elective induction of labor at 39 weeks, but after reviewing the literature, he saw that it was “…overwhelmingly evident that elective induction of labor is the logical strategy.”

The medical professionals in attendance at the meeting were convinced by this presentation, with a total of 81% of the attendees said they changed or reconsidered their views on induction at 39 weeks. The following statistics illustrate the opinions of the attendees before and after the presentation:

  • Percentage who believed that it is best to deliver most women at 39 weeks: 20% vs. 70%
  • Percentage unsure: 17% vs. 21%
  • Percentage who were against the idea of induction at 39 weeks for most women:  63% vs. 9%

Risks of Stillbirth After 39 Weeks Higher Than Anticipated

According to Dr. Norwitz, higher rates of stillbirths have been reported since the late ‘80s. He also points out that the risk of stillbirth increases at 40 weeks’ gestation and beyond. According to one BMC Pregnancy and Childbirth study, there were at least 26,000 stillbirths in the U.S. in 2004. He explains: “Antepartum fetal deaths account for more perinatal deaths than do complications of prematurity or SIDS.” He then points to a study in the British Journal of Obstetrics and Gynaecology that indicates that the risk of stillbirth and neonatal mortality increases with each passing week of gestation.

While researchers have not yet fully uncovered the reasons for this uptick in stillbirth rates, it is theorized that this could be due to uteroplacental dysfunction (as in the case of postmaturity syndrome), but could also be due to medical errors, which can include medical professional’s’ failure to identify risk factors for stillbirth and adverse pregnancy outcomes, including:

  • Multiple pregnancies
  • Infertility
  • Low blood pressure
  • Intrauterine growth restriction (IUGR)
  • Prior history of delivering a low-birth-weight baby

Concerns About Increasing C-Section Rates Unfounded

While a failed induction required a C-Section delivery, the researchers found that induction at 39 weeks did not actually increase C-Section rates, and may even have decreased them in comparison with simply waiting for spontaneous birth.

Some studies indicated that C-section rates increased in pregnancies involving multiple babies and unfavorable cervical exam results. However, the data that compares C-Sections and other outcomes between women induced at 39 weeks vs. those who had ‘expectant management’ at 31 weeks is sparse. In order to make solid conclusions, data from 2-12 million pregnancies would be needed. To circumvent this dearth of data, the team conducted a study known as a “comparative effectiveness analysis,” where they evaluated 60 possible conceivable outcomes and used a Monte Carlo microsimulation to map out “head-to-head” effectiveness. They found that waiting for spontaneous birth was associated with a higher rate of perinatal mortality and stillbirth. Groups that received induction at 39 weeks had lower rates of severe complications for both mother and child.

Overall, this report clearly states that “elective induction at 39 weeks is always a better strategy” than expectant management at 41 weeks, according to the speakers. They did caution, however, that successful induction is dependent on the physician accurately dating gestational age. According to Dr. Lockwood, “If you’re off, you could endanger the patient.”

The Bottom Line: ACOG is Changing its Perspective to Better Serve Patients

ACOG’s revision of their guidelines signals a change in their stance – one that is better for mothers and their children. A 2006 paper by ACOG stalwart and MFM  Gary Hankins stated that

infants born to nonlaboring women delivered by cesarean section [at 39 weeks] had an 83% reduction in the occurrence of moderate or severe encephalopathy …[The] net difference in moderate to severe encephalopathy would represent 9462 cases annually in the United States that could be prevented with elective cesarean section [emphasis added].

While the newly-revealed ACOG guidelines do not go so far as to recommend C-section at 39 weeks, this is a step in the right direction. The adoption of these new 39-week guidelines by obstetricians and gynecologists throughout the United States would decrease the rates of stillbirth, adverse outcomes, and significantly decrease the rate of hypoxic-ischemic encephalopathy (HIE).

Legal Help for Errors in Induction and C-Section

If you had an induction or a C-Section and suspect that your physician made a mistake that resulted in your child’s injury, developmental delays or cognitive/motor/learning disabilities, it may be worth it to consider speaking to a birth injury attorney about how to secure care for your child. Feel free to call Reiter & Walsh for a free case evaluation, and to discuss your legal options. We are available 24/7 and can be contacted via phone call, contact form, email or live chat.

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