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22: Changes in the patterns and rates of term stillbirth in the USA following the adoption of the 39-week rule: a cause for concern?

      Objective

      Because of reported associations between early-term delivery and various neonatal morbidities, an obstetric guideline called “the 39-week rule” was formally implemented in 2010 throughout the USA. The rule restricts “non-indicated” planned delivery prior to 39 weeks of gestation. However, several publications have suggested that the rule, by increasing the mean gestational age of term delivery, might increase population rates of term stillbirth. The objective of this large study was to determine if implementation of the 39-week rule was associated with an increase in the USA rate of term stillbirth.

      Study Design

      Sequential ecological study, using state data, of the patterns and rates of term live births and term stillbirths within the USA between 2007 and 2013, inclusive.

      Results

      Usable datasets were obtained from 46 states. Between 2007 and 2013 there was a continuous decrease in the proportion of term deliveries occurring in the 37th and 38th weeks of gestation. Over the same interval there was a continuous increase in the rate of term stillbirth (slope: 0.0186/1000/year, 95% CI 0.002-0.035). When comparing the 2007-2009 period to the 2011-2013 period, the rate of USA term stillbirth increased from 1.103/1000 to 1.177/1000 (RR 1.067, 95% CI 1.038-1.096).

      Conclusion

      Between 2007 and 2013 in the USA, the implementation of the 39-week rule achieved its primary goal of reducing the proportion of term births occurring before the 39th week of gestation. During the same period the rate of USA term stillbirth increased significantly. Assuming 3.5 million term USA births per year, more than 300 more term stillbirths occurred in the USA in 2013 as compared to 2007. This study raises the possibility that the 39-week rule may be causing serious unintended harm. Additional studies measuring the possible impact of the implementation of the 39-week rule on major childbirth outcomes are urgently needed. Pressures to enforce the 39-week rule should be reconsidered pending the findings of such studies.
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