Two new studies answer important questions about the process of giving birth. The findings may help pregnant women, working with their obstetricians, make choices that will benefit their health and that of their babies.

Does the timing of pushing affect C-section rates?

Obstetricians have differing opinions about when women should begin pushing during labor and whether the timing of pushing increases the likelihood of a cesarean section (C-section), a procedure that carries a higher risk of complications compared with a vaginal delivery.

ALISON CAHILL, MD, TALKS WITH PATIENT KAYLEE PRESTIEN. CAHILL LED A NATIONAL STUDY OF 2,400 FIRST-TIME PREGNANT WOMEN. FINDINGS SHOWED THAT THE TIMING OF PUSHING DURING LABOR AND DELIVERY HAS NO EFFECT ON WHETHER WOMEN DELIVER VAGINALLY OR BY C-SECTION.
Photo by Matt Miller, Washington University School of Medicine

Many obstetricians recommend that a woman begin pushing as soon as the cervix is fully dilated, while others advise waiting until she feels the urge to push. Until now, doctors have not had conclusive evidence about which approach is better for mothers and babies. Recently, a multicenter study led by Washington University School of Medicine and involving more than 2,400 first-time pregnant women, showed that the timing of pushing has no effect on whether women deliver vaginally or by C-section.

“The findings provide strong evidence that for first-time pregnant women receiving epidurals, immediate versus delayed pushing during the second stage of labor did not affect vaginal delivery rates,” says Menachem Miodovnik, MD, a medical officer at the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institutes of Health (NIH).

In fact, the study showed that women who delayed pushing experienced longer labors and higher risks of severe postpartum bleeding and infections. Their babies also were more likely to develop sepsis—a serious complication related to infection. “Obstetricians tend to favor one approach over the other, but no solid evidence has existed to favor either one,” says the study’s first author, Alison Cahill, MD, a maternal-fetal medicine specialist at the Women & Infants Center, a collaboration by Barnes-Jewish Hospital, Washington University Physicians and St. Louis Children’s Hospital. “We think our findings are likely to change how many obstetric providers manage labor.”

he study enrolled 2,414 first-time pregnant women at one of six U.S. hospitals. The women were at least 37 weeks pregnant with a single pregnancy, and all received epidural anesthesia to reduce labor pain. Once the cervix was fully dilated at 10 centimeters, indicating the beginning of the second stage of labor, each participant was randomly assigned to either begin pushing immediately or to delay pushing for 60 minutes.

INDUCTIONS AT 39 WEEKS LOWERED, NOT RAISED, THE NUMBER OF DELIVERIES BY CESAREAN SECTION.”

Of those in the immediate-pushing group, 1,031 (85.9%) delivered vaginally compared with 1,041 (86.5%) in the delayed-pushing group—a difference that is not statistically significant. However, women in the immediate-pushing group experienced significantly lower rates of infections and fewer episodes of excessive bleeding following delivery. Additionally, women who pushed immediately experienced a shorter second stage of labor by an average of 30 minutes, compared with those who delayed pushing. Although the numbers were small, infants delivered to mothers in the immediate-pushing group experienced significantly lower rates of suspected sepsis compared with those in the delayed-pushing group: 38 (3.2%) and 53 (4.4%), respectively.

Pushing during labor is physically demanding and intense,” says Cahill, who delivers babies at the Women & Infants Center. “Women look to their obstetric providers for guidance and what’s best for them and their babies. Our findings can guide providers to better manage the second stage of labor for optimal health for moms and their babies. This means avoiding delayed pushing for the sake of increasing the chance of vaginal delivery since delayed pushing is associated with longer labor time and higher health risks to mothers and babies.”

Does inducing labor at 39 weeks increase C-section rates?

According to a multicenter study funded by the NIH, the answer to this question is no: Inducing labor in healthy first-time mothers in the 39th week of pregnancy results in lower rates of C-sections compared with waiting for labor to begin naturally at full term. Additionally, infants born to women induced at 39 weeks did not experience more stillbirths, newborn deaths or other major health complications. “The concern has been that inducing labor—even at 39 weeks—would increase the cesarean-section rate and health problems in newborns,” says George Macones, MD, the study’s senior author and the head of the Department of Obstetrics and Gynecology at Washington University School of Medicine. Instead, he says, the study found that “inductions at 39 weeks lowered, not raised, the number of deliveries by cesarean section.”

DELIVERING BY C-SECTION GENERALLY IS CONSIDERED SAFE FOR MOTHER AND BABY. HOWEVER, THE PROCEDURE INVOLVES MAJOR SURGERY AND, THEREFORE, POSES INCREASED COMPLICATION RISKS AND LONGER RECOVERY TIMES FOR MOTHERS COMPARED WITH WOMEN WHO DELIVER VAGINALLY.

Delivering by C-section generally is considered safe for mother and baby. However, the procedure involves major surgery and, therefore, poses increased complication risks and longer recovery times for mothers compared with women who deliver vaginally. The study enrolled about 6,100 healthy, first-time mothers-to-be at 41 hospitals. About half of these participants were randomly assigned to labor induction at 39 weeks, while the other half waited for labor to begin naturally. Some women in the latter group were induced after 39 weeks for medical reasons. Of those who were induced at 39 weeks, 569 (18.6%) had C-sections compared with 674 women (22.2 %) who delivered by cesarean after waiting for labor to occur naturally—a difference that is statistically significant. Other health benefits experienced by women in the induced-labor group included reduced rates of pregnancy-related hypertension and postpartum infections.

And infants born to both groups of mothers had the same risks for complications such as newborn death, seizure, infection, injury and the need for infant respiratory support. Of the women in the induced-labor group and the spontaneous-labor group, 132 (4.3%) and 164 (5.4 %), respectively, experienced birth complications that affected their babies’ health. The difference between the two groups is not significant.

“Our findings offer healthy, pregnant women options for labor and delivery,” Macones says. “However, the choice always remains theirs.”

Originally published by Washington University School of Medicine at medicine.wustl.edu/news