The optimal timing of birth in a low-risk pregnancy is a continuing source of discussion, with health care providers seeking to balance risks to the woman and fetus. Research has shown that worse perinatal outcomes are associated with birth before 39 weeks but also that infant mortality risk increases after 39 weeks. Some obstetrics and gynecology experts have thus expressed support for the elective induction of labor at 39 weeks. Yet there has been concern that a failed induction could increase the need for a cesarean delivery.
Results of the ARRIVE (A Randomized Trial of Induction Versus Expectant Management) Trial published recently in the New England Journal of Medicine indicate that this is not the case. Researchers conducted the largest randomized trial ever to assess the impact of induced labor at 39 weeks in low-risk nulliparous women. They concluded that labor induction didn't increase the cesarean section rate; in fact, women who were induced were less likely to have a cesarean delivery. They also found that although there was no statistical difference in perinatal mortality and severe neonatal morbidity among infants born to women who had been induced at 39 weeks compared with those who had not, rates were lower among infants of women who had been induced.
A total of 3,062 women were randomized to the labor induction group and 3,044 were assigned to the expectant-management group. The trial was conducted at 41 centers within the National Institute of Child Health and Human Development's Maternal-Fetal Medicine Units Network. The primary outcome, a composite of perinatal death and severe neonatal complications, occurred in 4.3% of neonates in the induction group and in 5.4% of those in the expectant-management group. The difference appears to have been driven by a lesser need for respiratory support among neonates whose mothers were induced. In addition, the researchers noted that women who were induced had significantly fewer cesarean sections (18.6% versus 22.2%), which was the principal secondary outcome, as well as fewer diagnoses of hypertensive disorders of pregnancy (9.1% versus 14.1%). In their conclusion, the authors didn't suggest that elective labor induction at 39 weeks should become standard practice but rather that it did not increase the risk of adverse outcomes.
The lead author of the study, William A. Grobman, MD, the Arthur Hale Curtis, MD, Professor of Obstetrics and Gynecology at Northwestern University's Feinberg School of Medicine in Chicago, explained in an interview that the study has several take-home messages. "There is no good evidence that induction at 39 weeks substantively worsens maternal or perinatal outcomes or increases rates of cesarean delivery," he says. "There is evidence from this trial, as well as correctly designed observational studies, that it may slightly decrease cesarean rates and improve some perinatal and maternal outcomes." Therefore, women should be able to have "options regarding the timing of birth at or after 39 weeks and have this issue discussed in a way that relies on evidence, maximizes patient autonomy and agency, and relies on shared decision making," Grobman adds.
LINGERING CONCERNS
Questions remain as to how these findings will translate into clinical practice and whether they will lead to more elective inductions. There are also concerns about the potential of "over-medicalizing" labor in low-risk women who are having normal pregnancies without any complications.
In an accompanying editorial, Michael F. Greene, MD, of the Department of Obstetrics and Gynecology at Massachusetts General Hospital in Boston, highlighted a few caveats, focusing on the demographics of the women enrolled in the study. On average, participants were younger than the typical U.S. mother (median age, 23 to 24 years versus 28.7). Only 4.1% of trial participants were age 35 or older compared with 17% of all U.S. mothers. The women in the trial were also more likely to be black or Hispanic than white, compared with the general population. Greene speculated on the implications of the demographics, particularly in terms of the applicability of the study results and how U.S. mothers might feel about the induction of labor at 39 weeks. He also noted that more than 16,000 eligible women declined to participate in the study.
Regardless, says Grobman, the study results are generalizable. "I think it is fair to say that there are likely few if any randomized controlled trials in which the population literally mimics the exact proportions of the U.S. population," he said. "But I don't think that is the question[horizontal ellipsis] rather, the question is whether the study included different types of women within the United States, and whether there is any evidence that different subgroups had different associations with the outcomes." He explained that the study included women of all ages, even if the exact proportion of women in the general population who are older than age 35 differs, for example. The researchers also evaluated the effect of age, body mass index, race and ethnicity, and other variables on outcomes, and these made no difference to their findings.
Regarding the number of women who chose not to be included in the trial, Kathleen Rice Simpson, PhD, RNC, CNS-BC, FAAN, a perinatal clinical nurse specialist and editor-in-chief of MCN: The American Journal of Maternal/Child Nursing, observes that the women simply may not have wanted their labor induced. "They just may not have been interested in being in this trial," she says.
NURSING IMPLICATIONS
Simpson noted that several challenges may arise if induction at 39 weeks becomes a more popular option. "The women in this study were rigorously followed according to guidelines[horizontal ellipsis] and there didn't appear to be an increased risk," she says. However, "if you don't have someone paying close attention, the outcomes are not going to be the same as in this study."
Another major issue is appropriate staffing. Although staffing guidelines vary among professional organizations, all agree that a woman being induced requires one-to-one nursing care. "If you are going to do one-to-one care and longer intrapartum care, who is going to staff that?" Simpson asks. "That is a big issue." Ensuring extra staffing is costly to the hospital, and induction is also more expensive for the patient and the payer. "We need to focus on the main outcome of the trial, which was if you want to be induced, it will not increase the risk of a cesarean section or lead to worse outcomes," she says. "But it's not a recommendation that all women need to be induced at 39 weeks."
Grobman agrees that labor time was longer, and more nursing time would be needed. However, he points out, it's "important to remember that postpartum time for both women and their children was less, and there is no doubt that the longer labor and delivery time is at least somewhat offset in terms of inpatient resources."
In response to the study, the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine released a joint statement noting that they have "reviewed the published results of the ARRIVE Trial and determined that it is reasonable for obstetric care providers to offer an induction of labor to low-risk women after discussing the options thoroughly, as shared decision making is a critical element."-Roxanne Nelson, BSN