A new study suggests that idea might be wrong.
The research, published in the New England Journal of Medicine, focuses on healthy, first-time mothers. More than 6,000 women in 41 hospitals were enrolled in the study and were randomized into two groups. About half were induced in the 39th week of pregnancy. The others were allowed to let their pregnancies progress beyond that time.
The study's outcome was a surprise: Women induced at 39 weeks were less likely to need a C-section than those who waited to let labor begin spontaneously — 18.6 percent for the induced group, compared with 22.2 percent for the other group. The outcomes for the babies were similar for the two groups: They had statistically equal rates of infection, need for respiratory support, hemorrhage, stillbirth, newborn death or other major complications.
Uma M. Reddy, a doctor with the pregnancy and perinatology branch of the National Institute of Child Health and Human Development (NICHD), which funded the study, said it suggests that "one C-section could be avoided for every 28 women who undergo induction at 39 weeks."
The high rate of C-sections in the United States — 1 in 3 of all births — has created worry in recent years that the procedure is being overused. While the surgery is generally considered safe, it carries a risk of bleeding, infection and other complications that can be life-threatening. With the high rate of maternal mortality in the United States, which is much higher than in most other industrialized nations, there has been a desperate scramble by public health officials to try to understand the reasons, and the role of C-sections is still being studied.
The study's authors characterize the research as a game-changer for women suffering from discomforts of later-term pregnancies and for those who want to be able to schedule their deliveries for convenience's sake or to make sure their loved ones can be present.
But the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine emphasized that their review of the study showed only that it's now "reasonable" for obstetric-care providers to offer this as an option. ACOG's guidance remains unchanged: Induction without a medical reason should not be attempted before 39 weeks (when baby's lungs tend to be underdeveloped), and induction should be recommended after 41 weeks (when the risk of problems related to the placenta, amniotic fluid, umbilical cord go up for the baby and the risk of a condition known as preeclampsia goes up for the mother).
Errol Norwitz, chair of obstetrics and gynecology at Tufts University School of Medicine, expressed similar thoughts.
"I don’t think the conclusion of this paper should be we should be recommending or encouraging induction at 39 weeks. But if someone comes to you and desires to be induced, it is a conversation we should now be having," Norwitz said.
About a quarter of U.S. women end up inducing labor, many because of medical reasons but also by choice. The main risk is related to the hormone oxytocin, said Charles Lockwood, dean of the Morsani College of Medicine at the University of South Florida. If it is given too frequently or at too high a dose, the uterus could contract too much and reduce the blood flow to the placenta. If oxytocin is not given long enough, the labor will fail and doctors will have to do a C-section.
Lockwood published a previous paper in PLoS One on this question that used mathematical modeling to come to the same conclusion that 39 weeks may be best time to induce. He said that such results raise questions about why labor doesn't always begin naturally at the optimal point in the pregnancy. He speculated that, if there is an increase in complicated deliveries today, it could be because we are better fed so babies might develop faster than in the past, or perhaps it has to do with the fact that women are having babies at older ages. This is why, he suggested, we may be having so many problems now despite advanced medical technology.
"Nature isn't all that efficient as an obstetrician; otherwise there wouldn’t be so many Victorian novels about deaths in childbirth," he said.
One thing the study doesn't delve into is the cost implications of earlier induction. Women who induce spend more time on labor and delivery, so it can be more resource-intensive for hospital systems. However, the length of stay in a hospital is shorter when women are induced because of the lower number of C-sections.
Reddy emphasized that there's no one right answer to when a woman should induce: "The decision about when to deliver is very individual."
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