Pregnant women who are near their due date or have just passed it can have labor induced with drugs or other medical procedures — or they can simply wait for labor to start on its own.
Sometimes, there is a medical reason to induce labor, such as a woman having gestational diabetes, but in other cases, women undergo elective induction, when labor is induced without a medical reason. Now, a new study suggests that women who elect to induce labor are less likely to wind up having a cesarean section (or C-section) compared with women who give labor a longer chance to begin naturally.
Among women in the study who had previously had a baby, the odds of having a C-section for their current pregnancy were cut by about half in those who underwent elective induction. About 3 percent of these women who were induced wound up having a C-section, while about 7 percent of those who waited for labor to start on its own had the surgery, said study researcher Blair G. Darney, an obstetrics and gynecology researcher Oregon Health & Science University.
The reduction in C-section risk was less pronounced but still seen in women in the study having their first baby, Darney said. About 26 to 29 percent of women having their first baby who waited for labor to start had a C-section, while 18 percent to 25 percent of those who elected to induce their labor had the surgery. (All women in the study were at least 37 weeks pregnant; the exact percentages of women undergoing C-sections varied depending on how far along in their pregnancies they were.) [ Blossoming Body: 8 Odd Changes That Happen During Pregnancy ]
"Our study suggests that when physicians counsel pregnant women at term (37-40 weeks) about the risks and benefits of elective induction, women should not be told that induction will definitely increase their risk of cesarean delivery," Darney told LiveScience in an email.
Previous studies have suggested the opposite to be the case: In that research, women who are induced at term without a medical reason were found to be more likely to give birth via cesarean section. Such studies compared women who were induced with women whose labor eventually began naturally, Darney said.
The new study was different in that the researchers compared women who, at a given time, either waited or were induced. (Some of those who waited eventually were induced, for either medical or elective reasons.) "Our study compared women who were induced to women who remained pregnant, and we found that induction does not increase the risk of cesarean delivery, and may actually lower that risk," Darney said.
Over the last 20 years, there has been an increase in labor inductions in the United States. But it remains unclear how induction in women whose pregnancies have reached term may affect the mother's or baby's health.
The American College of Obstetricians and Gynecologists has recommended reducing inductions done before 39 weeks of pregnancy without medical reason, and studies have shown such reductions decrease admissions to the neonatal intensive care unit (NICU).
While one of the key concerns surrounding inductions done without a medical reason is that they might increase the rate of C-sections, little is known about the risk, the researchers wrote in their study.
In the new study, the researchers looked at hospital discharge data from all deliveries in California in 2006, excluding women who had a prior cesarean delivery. About 360,000 births were included in the study, and the researchers compared the roughly 17,000 women who were induced for nonmedical reasons to the women who, during each progressive week of pregnancy, opted to take the wait-and-see approach for at least one more week.
When the researchers took into account factors that might influence induction or C-sections, the link between induction and fewer C-sections remained.
Induction of labor was not linked with higher odds of death, NICU admission or respiratory distress, the researchers said.
The researchers compared the characteristics of the women who elected to be induced with those who waited; they found that women who were induced tended to be white, have more education and had received better prenatal care. The study didn't address why these demographic differences exist, Darney said, and future research should look at that question.
"Our study adds to a growing number of studies that question the accepted wisdom that induction increases the risk of cesarean delivery," Darney said.
The study was published Monday (Sept. 9) in the journal Obstetrics and Gynecology.