When a near-term fetus is expected to be larger than most other newborns at birth, it might be safer to induce labor a bit ahead of the due date, new data suggest.
Births of large babies can be complicated by shoulder dystocia, an emergency situation in which their shoulders become impacted on the mother's pubic bones after their head has emerged, preventing the rest of the body from being delivered spontaneously.
o see if inducing labor ahead of schedule would reduce the risk of shoulder dystocia, researchers recruited 2,893 women whose fetuses appeared on ultrasound to be larger than 90% of other similarly-aged fetuses.
They randomly assigned the women to receive standard care or induction between 38 weeks and 38-weeks-and-four-days of gestation. Induction was expected to result in an earlier birth and a lower birth weight than standard care.
Overall, in the so-called Big Baby Trial, there was no difference between the groups in rates of shoulder dystocia, probably because many of the women in the standard care group delivered before 38 weeks, and so their babies were smaller than predicted.
When the analysis was limited to women who did not deliver before 38 weeks, shoulder dystocia occurred in 2.3% of babies in the induction group versus 3.7% of those in the standard care group.
The induction group delivered on average about 8 days earlier, and their babies weighed about 8 ounces (213 grams) less, compared to the usual-care group.
After accounting for individual risk factors, the odds of shoulder dystocia were 38% lower in the induction group versus usual care in women whose pregnancies lasted beyond 38 weeks.
Induction of labor was also associated with a lower likelihood of cesarean delivery and fewer maternal complications, researchers reported in The Lancet.
An editorial published with the report notes, “The Big Baby Trial joins an accumulating body of literature... indicating that induction of labor either does not alter or might reduce the risk for needing cesarean delivery” when a larger fetus is suspected.