The effect of maternal age on fetal and neonatal mortality.

OBJECTIVE: Determine the gestational age at which the risk of fetal or neonatal death associated with delaying delivery by 1 week exceeds the risk of neonatal death associated with immediate delivery, stratified by maternal age intervals.

STUDY DESIGN: We conducted a retrospective cohort study of live births, stillbirths and neonatal deaths that occurred in the United States between 2010 and 2013 using birth data. Women were classified into six age categories. Singleton, non-anomalous pregnancies without hypertensive disease or diabetes were included. Relative risks were obtained using a generalized linear model comparing the rate of death associated with immediate delivery to those of expectant management.

RESULTS: For all age groups with the exception of women 44 years and older, immediate delivery was associated with lower relative risk of death by 39 weeks. For <25, 25 to 29, 30 to 34, 35 to 39, 40 to 44, odds ratios (OR) and confidence intervals (CI) were 1.0 (0.32 to 3.10), 0.67 (0.19 to 2.37), 0.80 (0.21 to 2.98), 0.67 (0.19 to 2.36) and 0.45 (0.16 to 1.31), respectively. In women 44 years and older, immediate delivery was associated with a lower relative risk of death by 38 weeks (OR: 0.35, CI: 0.14 to 0.90).

CONCLUSION: Women greater than 44 years old may benefit from delivery by 38 weeks gestational age to reduce the risk of stillbirth.