If labor needs to be induced, it should be done in the morning rather than the evening.
That’s because this more closely reflects the natural timing of labor and is associated with less-complicated births, suggests a study in the August issue of Obstetrics & Gynecology.
“Women should be informed of these results, and given the opportunity to decide themselves” at what time they want to be admitted, said study author Dr. Jodie Dodd, maternal fetal medicine subspecialist at the University of Adelaide School of Pediatrics and Reproductive Health, in South Australia.
“At the Women’s and Children’s Hospital in Adelaide, we are in the process of updating our induction of labor guidelines to include this information,” she added.
However, other experts said the issue isn’t quite this simple.
“There are a lot of factors that go into deciding when to induce a patient,” said Dr. Jennifer Wu, an obstetrician/gynecologist at Lenox Hill Hospital in New York City. “You have to coordinate with the available slots, with the doctor’s schedule, the patient’s schedule, sometimes something looks suspicious on a test.”
Previous research has consistently shown that spontaneous birthing tends to peak in the evening and early hours of the morning, according to background information in the study.
At the University of Adelaide, women scheduled for induction are admitted in the evening, with the expectation that they will labor and give birth during daylight hours. This is often more convenient for family and staff.
The new study involved 620 women, all of them scheduled for induced labor. Participants were randomly assigned for admission at 8 a.m. or 10 p.m. Two hundred-eighty women were in the morning group and 340 in the evening group.
There were no statistically significant differences between the two groups in the main results: number of women who were in labor beyond 24 hours, uterine hyperstimulation, and fetal heart rate changes or Caesarean-section deliveries.
But women admitted in the morning were less likely to need an infusion of the hormone oxytocin to induce labor — 45 percent in the morning group vs. 54.1 percent in the evening group.
But oxytocin is only one type of medicine that can be used to induce labor, Wu said. “There are many different types of medication to use for induction,” she said.
Women delivering for the first time and who were admitted in the morning were also less likely to require operative vaginal birth — 16.1 percent in the morning group vs. 34.2 percent in the evening group.
The researchers could not pinpoint the reason for these differences. “It is unclear if these findings reflect physiological differences, or whether it reflects differences in clinical practice that may occur by staff during the day and during the night,” Dodd said.
There were no differences between the two groups in maternal satisfaction with the delivery practice, although women in the evening group generally disliked the interruptions and lack of sleep they suffered.
While the study authors assume that morning admissions lead to evening deliveries, this is not always the case, Wu pointed out.
“There are a lot of patients we induce in the morning who deliver by 2 p.m.,” she said.