Researchers Link Labor Induction and Shoulder Dystocia

Results of a recent study reveal that inducing labor may benefit some women who are pregnant with unusually large infants, as it may reduce the odds of shoulder dystocia. Typically, doctors don’t induce labor before a child is full term at 39 weeks, as early deliveries can cause breathing problems and other complications for babies.

However, if an oversized infant’s shoulders become lodged in the birth canal, they can sustain serious injuries. The research team examined the impact of inducing labor at 37 to 38 weeks, to see if stopping the infants from growing larger would make for a safer delivery.

“I believe that the benefits of induction outweighed the potential risk of an early term birth” for the small percentage of infants who are exceptionally large, lead author Dr. Michel Boulvain, of the department of obstetrics and gynecology at Geneva University Hospitals in Switzerland, said by email to Fox News.

Shoulder dystocia study

Boulvain and his team examined labor induction as way to reduce instances of shoulder dystocia. This condition can occur during a vaginal delivery, when the baby’s shoulders get stuck inside the mother’s body. Dystocia means difficult or slow labor and can be risky for both the mother and the child. While it can be dangerous, doctors cannot typically prepare for or prevent this disorder. It is often only discovered after labor has started, when it’s too late to have a cesarean section. A complicated delivery with shoulder dystocia may result in birth injuries for the infant, including nerve damage in the spine and brachial plexus, as well as suffocation during delivery.

Labor induction may decrease risk of shoulder dystocia

The research team studied sonograms to find more than 800 women with babies in the 95th percentile for weight, based on their gestational age. Approximately half the women were randomly selected for labor induction, while the rest were closely monitored until going into labor naturally or when induction was necessary due to other medical issues.

The 800 women were patients at 19 university hospitals in Belgium, France and Switzerland. In total, labor was induced in 366 of the 409 women in the induction group and in 116 of the 412 women in the group being monitored. Two percent of the infants in the group assigned to labor induction suffered shoulder dystocia, rising to six percent in the group that was closely monitored. Cesarean rates between the two groups were the same.

The authors of the study admit to its limitations, including the fact that the group was smaller than originally hoped, as it was challenging to get women to join. Additionally, using sonograms later in pregnancy to estimate the weight of a baby can be inaccurate, writes the research team in The Lancet.

According to Boulvain, waiting to induce labor until 39 weeks or after may decrease the chances of preventing shoulder dystocia. By this late point in a pregnancy, intervening may have a smaller chance of decreasing the infant’s birth weight or preventing injuries than doing so one or two weeks earlier.

“Then, the balance between benefits and risks may swing the other way,” Boulvain said.

The findings from the study reveal that women and their doctors need to strike a balance between the use of induction at 37 to 38 weeks to prevent potentially serious injuries to infants and avoiding delivering before 39 weeks, as that can also prove dangerous, wrote Dr. Aaron Caughey, an obstetrician and gynecologist at Oregon Health and Science University in Portland, in an editorial accompanying the study.

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