A new study has found that inducing women who are 39 weeks pregnant — instead of waiting until the full-term 40-week mark — may actually lower the risk of Caesarean sections. These results run contrary to the prevailing wisdom that inducing labor increases the risk of complications, which lead to more C-sections, putting both the baby and the mother at risk.

Women induced at 39 weeks, research published in the New England Journal of Medicine found, were less likely to need a C-section than those who waited to let labor begin spontaneously.

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 this suggests that “one C-section could be avoided for every 28 women who undergo induction at 39 weeks.”

How the study was conducted

The study focused 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.

It turned out that 18.6 percent of the induced group required C-sections, compared with 22.2 percent of 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.

The high rate of C-sections in the United States — which account for about 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.

What does this mean for soon-to-be mothers?

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 medication 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.

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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