I wish to express concern about the article by Nicholson et al suggesting that from 2007 through 2013, the adoption of the 39-week rule caused a progressive reduction in the proportion of preterm births occurring before the 39th week of gestation, while concurrently contributing to a significant increase in the rate of term stillbirths experienced in the United States. The authors asked if the 39-week rule should be continued and if it is a cause of concern. Despite this sequential ecological study based on some, but not all, state data of term deliveries, I respectfully disagree with the authors’ conclusions. Institution of the 39-week rule has gone far in reducing unnecessary preterm and early term births. Further, according to conflicting findings and publications, some even during a similar time period, it has not increased the stillbirth rate (which has remained steady despite the 39-week rule).
Confounding factors and unknown data could have and probably did contribute to the increase in the rates of term stillbirth reported in this study. These include but are not limited to: the use of antenatal testing, an increase in out-of-hospital births, poor obstetrical dating, the reason for the stillbirth, missing data, and patients delivered at 39 weeks who actually should have been delivered in the late preterm/early term time period for medical indications. We should continue to avoid nonmedically indicated deliveries <39 weeks’ gestation because this increases neonatal risk. The benefit of reduction of preterm neonates with morbidity is proven. During the early years of the institution of the 39-week rule, practitioners were reluctant to deliver any neonates, even those with a medical indication, <39 weeks. This practice could have contributed to the term stillbirth rate. Additionally, the 39-week rule has been misapplied to higher risk pregnancies, which represent a unique and clearly separate patient population and data set. Clearly, the 39-week rule does not indicate that all deliveries <39 weeks of gestation are contraindicated.
This study also asserted that a moratorium should now be considered because the 39-week rule might be causing unintended harm. However, a collection of articles reported just the opposite. I would suggest, as have others, that harm is not caused by the 39-week rule, when used in low-risk pregnancies. Further research, including adequately powered, randomized clinical trials providing clear and convincing data to the contrary, is needed before removing the 39-week rule from obstetric practice. Given the available evidence of clear benefit in the reduction of neonatal mortality in early term and late preterm infants, and differing conclusions from a number of studies on questionable increase in stillbirth rate, it seems reasonable to await future research and continue the 39-week rule. Yes, there is a cause for concern, but let’s not throw the baby out with the bathwater.