induce labor

A new study evaluated if choosing to induce labor lowers the frequency of C-sections and reduces the risk of complications compared to waiting for spontaneous labor.

There has been a steady rise in the number of Cesarean sections (C-sections) for the delivery of a baby. In the United States, healthy, first-time mothers may go through C-sections that in some cases may be medically unnecessary.

Cesarean delivery is a major surgery. Although it is usually safe for the mother and the baby, recovery after the surgery is long and difficult compared to vaginal delivery. In addition, a C-section may increase the risk of vaginal delivery problems in future pregnancies.

Inducing labor has gained popularity in recent years for convenience. However, labor should be induced when it is harmful for the baby to stay in the uterus any longer. The health care provider can use various methods to induce labor such as medication or breaking the amniotic sac to stimulate contractions. In case of medical reasons to induce labor, it is best to wait until at least 39 weeks of pregnancy.

Past research suggested inducing labor could lead to C-sections

The observational studies conducted in the past compared labor induction with spontaneous labor. These comparisons concluded that inducing labor could lead to Cesarean delivery. However, some researchers believe that these comparisons were not clinically relevant and did not provide a better understanding of the clinical management of labor and delivery.

Comparing labor induction with expectant management

The researchers argue that a comparison of labor induction with expectant management is clinically more relevant. Expectant management of labor allows the pregnancy to progress to a full gestational age without any interventions. The ARRIVE trial conducted in 41 hospitals of the US was designed to test this comparison between induced labor and expectant management. The study published in the New England Journal of Medicine recruited 6106 healthy first-time mothers.

The participants were divided into two groups. The first group of 3,062 women was assigned to the labor induction group in which the researchers would stimulate contractions at 39 weeks of pregnancy when the baby is full term and it is safe to give birth.

The second group of 3044 women was assigned to the expectant management group, which involves watchful waiting. In this group, participants would wait for labor until the due date but no later than 42weeks without any interventions.

The researchers examined the babies for a few days after birth for conditions such as the Apgar scores, brain injury, infection, low blood pressure, and death. Maternal conditions were observed before, during and after birth. In addition to Cesarean delivery, the mothers were watched for indications for operative vaginal delivery, postpartum hemorrhage, infection, duration of labor, length of hospital stay, and death. 

No significant difference between labor induction and watchful waiting

In this randomized trial, the researchers observed no significant difference in the incidence of death or other health indicators of the newborn between the labor induction and expectant management group. The results indicate that labor induction is probably as safe as expectant management. Although the difference is not statistically significant, relative risk of adverse events was 20% less in the induction group compared to the spontaneous labor group.

Furthermore, the researchers observed a lower frequency of Cesarean delivery and high blood pressure disorders of pregnancy in the labor induction group compared with the expectant management group. Based on these results, the researchers believe that elective labor induction at 39 weeks in healthy first-time mothers could eliminate the need for one Cesarean delivery for every 28 deliveries. The results also showed that the newborns in the labor induction group needed a shorter duration of respiratory support and a shorter hospital stay. The age of women, ethnicity, and BMI had no effect on these findings.

This trial detected differences that past trials may have missed

The large size of this trial and a comparison between labor induction and expectant management in healthy women are the main strengths of this study.  These strengths give this trial the ability to recognize the differences that other trials in the past may not have detected.

Certain limitations of the trial include a chance of bias because it was not a blinded trial, inability of the trial to detect uncommon and infrequent outcomes, and uncertainty about the generalizability of the results. The researchers also expressed concern about the cost-effectiveness of labor induction at 39 weeks.

Pregnant women should talk to their health care providers

These results show that starting labor by stimulating contractions is as safe as spontaneous labor. Additionally, induction of labor may lead to fewer instances of Cesarean delivery. Therefore, health care policies that avoid induction of labor may not help reduce the rate of Cesarean delivery and choosing to induce labor should not be discouraged for fear of Cesarean delivery. Although this study does not change how babies are born it provides important information about the safety of inducing labor. In the end, starting labor using induction or waiting for spontaneous labor should be a shared decision between the pregnant woman and her health care provider.

Written by Preeti Paul, MS Biochemistry

Reference: William A. Grobman et al., Labor Induction versus Expectant management in low-risk Nulliparous Women. N Engl JMed 2018;379:513-23  DOI: 10.1056/NEJMoa1800566

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