Women take longer to give birth today than did women 50 years ago, according to an analysis of nearly 140,000 deliveries conducted by researchers at the National Institutes of Health.
The researchers compared data on deliveries in the early 1960s to data gathered in the early 2000s. They found that the first stage of labor had increased by 2.6 hours for first-time mothers. For women who had previously given birth, this early stage of labor took two hours longer in recent years than for women in the 1960s. The first stage of labor is the stage during which the cervix dilates, before active pushing begins.
Infants born in the contemporary group vs those from the 1960s
- Tended to weigh more
- Were born 5 days earlier, on average
Women today vs the 1960s
- Weighed more
- Were, on average, four years older at the time of birth
The women in the contemporary cohort had an average pre-pregnancy Body Mass Index of 24.9. A BMI of 25 is considered overweight. Overweight and obesity raise the risk of pregnancy complications for mother and baby. Women who are overweight or obese and who would like to become pregnant should speak with their health care provider about losing weight before becoming pregnant.“Older mothers tend to take longer to give birth than do younger mothers,” said the study's lead author, S. Katherine Laughon, M.D., of the National Institute of Child Health and Human Development (NICHD). “But when we take maternal age into account, it doesn't completely explain the difference in labor times.”
Changes in delivery practice the researchers found included an increase in the use of epidural anesthesia (half of recent deliveries, compared with 4 percent of deliveries in the 1960s.) Doctors in the early 2000s also administered the hormone oxytocin more frequently (in 31 percent of deliveries, compared with 12 percent in the 1960s), the researchers found. Oxytocin is given to speed up labor, often when contractions seem to have slowed. "Its use should be expected to shorten labor times, " Dr. Laughon explained, “ and without it, labor might even be longer in current obstetrics than what we found".
Other differences between the two groups reflect changes in later stage delivery practices. For example, in 1960s-era deliveries the use of episiotomy (surgical incision to enlarge the vaginal opening during delivery), and the use of forceps, surgical instruments used to extract the baby from the birth canal, was notably more common than they are today.
In current practice, doctors may intervene when labor fails to progress. This could happen if the dilation of the cervix slows or the active phase of labor stops for several hours, Dr. Laughon explained. In these cases, intervention can include administering oxytocin or performing a cesarean delivery.
In fact, the study found that the rate of cesarean delivery was four times higher today than it was 50 years ago (12 percent vs. 3 percent).
The authors note that while their study does not identify all the factors contributing to longer delivery times, the findings do indicate that current delivery practices may need to be re-evaluated.The study authors called for further research to determine whether modern delivery practices are contributing to the increase in labor duration.
Their analysis was published online in the American Journal of Obstetrics and Gynecology.