Association of Widespread Adoption of the 39-Week Rule With Overall Mortality Due to Stillbirth and Infant Death

1. Following the Joint Commission’s adoption of the 39-week rule to reduce early, elective deliveries, there has been a marginal significant increase in the stillbirth rate while overall mortality rates have remained relatively stable.

Evidence Rating Level: 2 (Good)

Studies on the association of mortality with the adoption of the Joint Commission’s 39-week rule have yielded inconsistent results thus far. While elective deliveries prior to the 39-week period may be associated with neonatal morbidity, prolonging pregnancy is also known to increase risk of stillbirth. This historical cohort study reviewed birth and infant death certificates in the United States to compare the preadoption period (2008-2009; n=7,322,234) with the postadoption period (2011-2012; n=6,972,626) of this rule. Births included in analyses were singleton and nonanomalous between 37 0/7 weeks’ and 42 6/7 weeks’ gestation. Investigators found a decrease in proportion of deliveries at 37 and 38 weeks and an increase in the proportion of deliveries at 39 and 40 weeks (p<0.001). The overall mortality rates during the preadoption and postadoption periods remained relatively stable (p=0.06) while the infant death rate decreased in the postadoption period (difference .01%, p<0.001). However, the stillbirth rate demonstrated a significant increase in the postadoption group compared to the preadoption group (difference 0.01%, p<0.001). Further analyses suggested that up to 34.2% of the reduction in mortality may be associated with the adoption of this rule. This study demonstrated that overall mortality rates remained steady during the two years following adoption of the 39-week rule even though there was an increase in stillbirth. While limited in terms of outcomes of interest in the groups studied, these findings suggest a need for further research on other variables that contribute to stillbirths while being offset by reduced infant deaths at term.

Click to read the study in JAMA Pediatrics

Image: PD

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