Labor induction doesn't decrease risk of C-section for full-term pregnancies, study finds
For years, there’s been a tension within the professional birthing community: does inducing labor in a healthy, full-term pregnancy lower the risk of a cesarean birth? New research in Michigan suggests it doesn’t, and that in some cases, inducing labor may actually increase the risk of a C-section.
“We found actually that people who had that elective induction of labor, had a higher rate of cesarean delivery,” said Dr. Elizabeth Langen, an associate professor of obstetrics and gynecology at the University of Michigan and the lead author of the study recently published in the American Journal of Perinatology.
Langen knows this directly contradicts what other major studies have found in the past. In 2018, a multicenter, randomized trial called the ARRIVE study followed roughly 6,000 women with full-term, uncomplicated pregnancies. Those who opted for elective inductions at 39 weeks had a significantly lower risk of C-sections, compared to those who didn’t. (There was no significant difference between the groups when it came to stillbirths or other serious medical complications.)
“It was a little bit of a surprise to people how much of a reduction they found in that study,” Langen said. “Lots of folks [in the medical community] started advocating for an induction of labor. But there is some tension there, because if you have an induction of labor, you will spend a lot more time in the hospital. You will have a lot more medical procedures done to you. And that's not always in everyone's best interest, and that's not always the birth that every woman or birthing person wants to have.”
So Langen’s team wanted to look at “real world” data: births that didn’t happen in the controlled, closely-watched confines of a clinical trial, where participants have to opt in and be comfortable with the prospect of an induction.
For most women, “prenatal visits tend to be very short,” Langen said. “We as health care providers try our very best to explain what will happen. But if this is your first baby and you've never birthed before, and you've got a 15 minute visit with your obstetrician or midwife, and you've got to talk about all kinds of different things, you might not be getting as much informed consent as those folks who had a trained research study team member sitting with you for as long as you needed, to explain the risks and benefits of having a labor induction… And it's quite different to be in a controlled randomized trial versus, just kind of in the world having a baby like most of us do.”
When someone’s pregnancy reaches 39 weeks, aka full term, they’ve got options. If they’re healthy and everything looks good (the baby’s head is down, meaning they’re in the safest position for birth; the mom’s blood pressure is at a good level, etc.) they can wait until they naturally go into labor. That’s known as “expectant management.”
Or, they can opt for an elective induction, meaning medical intervention to put their bodies into labor. Langen said she often meets with patients who were induced in the past, and are still confused about why.
“I'll see people for their subsequent pregnancies, and I'll ask why they were induced last time,” she said. “It's not at all uncommon for patients to not know why or for patients to tell me a reason that is very different from the reason that's in their medical record. Because it seems like there's just not perfect communication …The way our health care system is set up, it's not designed to give people lots of time to reflect and read back and make sure we're all on the same page about everything.”
So Langen’s team looked at more than 14,000 deliveries in 2020 in Michigan, analyzed through a statewide maternity care quality collaborative registry. These were healthy pregnancies where the woman was at 39 weeks, with a single pregnancy (not twins or triplets) giving birth for the first time, and the baby was in the head-down position.
What they found were two things: 1) about 30% of women who had an elective induction had a C-section, compared to 24% of those who chose expectant management. But 2) the women getting elective inductions tended to be a pretty select group: white women over the age of 35, with private insurance.
When controlled for those variables, there was no difference in the rate of C-section between the two groups (induction vs. expectant management). But there were other noteworthy findings as well: the women who didn’t get an elective induction at 39 weeks were slightly less likely to have a postpartum hemorrhage. Meanwhile, those who did choose elective induction were at slightly lower risk for a hypertensive disorder of pregnancy, like preeclampsia.
“The bottom line is, if you make it to 39 weeks of pregnancy and (it’s) your first baby, there is not any medical certainty about whether or not it's better for you to wait for labor to start, or for you to choose an induction of labor,” Langen said. Instead, she said, people should talk with their providers about what feels like the right fit for them.
“It has to do with a lot about how you envision your birth, and what type of risk and benefits are important to you. So if you choose a labor induction, you have some control about the timing and circumstances. And for some people that's very important. If you choose expectant management, you might be one of those folks who at 39 weeks and five days goes into labor on their own and has a quick, beautiful, easy, natural birth. But you are also taking the risk that you're going to be the person who is now pregnant a week past their due date and has high blood pressure and needs an induction that's going to be much more medicalized because of the complications that have arisen.”
The other big takeaway: pregnant women clearly aren’t treated the same, given the racial differences between the induction data. Langen’s not sure why older, white women with private insurance were so much more likely to undergo an elective induction.
“It is hard to guess,” she said. Maybe the older group, more likely to be white women, with private insurance, was able to afford more prenatal care, build a strong bond with their physician or midwife, and decided to schedule an induction so they could deliver with that provider. Or maybe those who were older received more pressure to induce labor rather than wait, or were simply more anxious about their births.
“We don't know if it was provider pressure for this group of people that they wanted them delivered at a certain time for various reasons, or if it was more patient-driven,” Langen said. But “there's a lot of inequities in how we provide care to pregnant and birthing people. So it's just important that we keep thinking about that: who are we harming, and who are we not? And who are we allowing to be in control of their own birthing experience?”