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Choosing to induce labor at 39 weeks reduces risk of C-sections, study finds

The new research contradicts a long-held belief that inductions lead to more complications, including more cesareans.
A technician performs an ultrasound on a pregnant woman. A new study finds that inducing labor in a healthy woman at 39 weeks lowers the risk of delivery by cesarean section.Ton Koene / VWPics via AP file

Inducing healthy first-time mothers at 39 weeks pregnant instead of waiting for them to go into labor on their own does not raise the risk of a cesarean delivery, a new study says. In fact, it lowers it.

The findings go against a long-held belief, based on prior studies, that induction can increase the likelihood of a C-section — surgery that carries a higher risk of infection or postpartum hemorrhaging than natural births.

For this trial, to be published in the New England Journal of Medicine on Thursday and sponsored by the National Institutes of Health, researchers tracked more than 6,100 women in 41 sites across the country. Half were given elective, non-medically necessary inductions in the week before their due dates, while the others waited for labor to start without any intervention.

Those induced at 39 weeks had lower rates of maternal and fetal complications, including fewer C-sections (19 percent vs. 22 percent); lower frequent preeclampsia, a potentially dangerous pregnancy condition, and hypertension (9 percent vs. 14 percent); and fewer newborns who needed respiratory support (3 percent vs. 4 percent).

The notion that inductions can lead to C-sections was based on past data comparing a woman who goes into labor spontaneously with a woman who is induced at the same point in her pregnancy — which could be before the 39th week, if complications developed, or when the woman was overdue and had gone past 40 weeks, said the study's principal investigator, Dr. William Grobman, a professor of OB-GYN at Northwestern Medicine.

In those studies, a link between induction and C-sections existed. But that's because they included so many different scenarios, he said.

"People misinterpreted that data" to mean that inductions at any point in a pregnancy carry more risk, Grobman said.

The researchers said they had an inkling that inductions in the 39th week for healthy women, when the risks to both mother and child are at their lowest points, would show different results.

"If you deliver the baby before 39 weeks, then there's an increased risk of medical problems," said study co-author Dr. Robert Silver, chairman of obstetrics and gynecology at University of Utah Health. "Once you get to 39 weeks, the baby's developed enough that there's really no benefit" to holding off.

The trial was the largest of its kind. The findings received a cautious endorsement from the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine.

"It is reasonable for obstetric care providers to offer an induction of labor to low-risk women after discussing the options thoroughly, as shared decision making is a critical element," the groups said in a statement, adding that this only applies to women with no complications who are delivering their first babies and have had an ultrasound early in pregnancy to confirm their due date.

Dr. Jessica Page, 33, an OB-GYN doctor at the University of Utah Hospital who gave birth herself for the first time 11 months ago, said inducing at 39 weeks felt right. She didn't participate in the study, but is a colleague of Silver's, and was aware of the emerging research on the topic. Her son, Paddy, was born without any problems when she was induced at 39 weeks.

Jessica Page
Dr. Jessica Page, an obstetrician in Salt Lake City, opted to be induced at 39 weeks to give birth to her son, Paddy.Courtesy of Jessica Page

"I felt like based on my knowledge as a provider but also counseling from my doctor that we were in a good spot," she said. "If my baby is ready to come out in terms of its maturation, what is there to be gained with waiting?"

Not everyone agrees. Susan Stone, president of the American College of Nurse-Midwives, a professional association with 7,000 members, urges mothers to consider more natural ways to try to prevent complications.

"It's going to be appropriate for some women, but the question is, how widely will this be applied, what is going to be the cost to our society of doing that, and could those costs be put to a better use that might be a more non-interventative strategy for reducing cesarean sections?" she told NBC News.

Cynthia Gabriel, a medical anthropologist, echoed that. She is the author of a book, "Natural Hospital Birth: The Best of Both Worlds," which advocates for a holistic birth in a hospital setting with as little medical intervention as possible.

"Personally, I would look at all the practices that we currently do that lead women to have different labors and more cesareans than necessary in their hospital births," she said, citing the 31.9 percent of deliveries in the U.S. that end in C-sections.

She suggested that mothers hoping to prevent complications hire a doula — a trained birth assistant — which studies have shown reduce the need for a C-section.

The new research comes at a crucial time for maternal care. Each year in America, about 700 women die as a result of pregnancy or delivery issues — while 50,000 experience severe complications, according to the Centers for Disease Control and Prevention.

The problems are particularly magnified for women of color. Black women are three to four times more likely than white women to die from pregnancy-related causes nationwide, the CDC says.

Minorities who participated in the study still experienced more adverse outcomes than their white counterparts overall. But those in the induction group also benefited from the elective induction, Silver said.

"There was reduced risk of cesarean and preeclampsia regardless of race or ethnicity, and there was reduction of pulmonary disease in the baby regardless of race and ethnicity," he said.

Induction isn’t right for every woman, the researchers say. Those who desire a more holistic approach should still plan for that, as long as their obstetrician deems it safe.

"People shouldn't be afraid to go past 39 weeks," Silver said. "This doesn't mean it's a better option and that everyone should be induced at 39 weeks. It simply means you aren't going to cause harm."