The following is a summary of “Risks of stillbirth, neonatal mortality, and severe neonatal morbidity by birthweight centiles associated with expectant management at term,” published in the OCTOBER 2023 issue of Obstetrics and Gynecology by Hong, et al.

Determining the optimal timing for childbirth at term poses challenges due to the ongoing risks of stillbirth with increasing gestation and the risks of significant neonatal morbidity at early-term gestations, particularly in small infants. For a retrospective cohort study, researchers sought to evaluate the risks of stillbirth, neonatal mortality, and severe neonatal morbidity by comparing expectant management with delivery from [37⁺⁰ weeks] of gestation.

The study included women with singleton, nonanomalous pregnancies at [37⁺⁰ to 40⁺⁶ weeks’] gestation in Queensland, Australia, delivered from [2000 to 2018]. Rates of stillbirth, neonatal death, and severe neonatal morbidity were calculated for different birthweight centiles. The composite risk of mortality with expectant management for an additional week in utero was compared with rates of neonatal mortality and severe neonatal morbidity.

Out of [948,895] singleton, term nonanomalous births, [813,077] occurred at [37⁺⁰ to 40⁺⁶ weeks’] gestation. Stillbirth rates increased with gestational age, reaching the highest rate in infants with birthweight below the third centile: [10.0 per 10,000 (95% CI, 6.2–15.3)] at [37⁺⁰ to 37⁺⁶ weeks], rising to [106.4 per 10,000 (95% CI, 74.6–146.9)] at [40⁺⁰ to 40⁺⁶ weeks’] gestation. The rate of neonatal mortality was highest at [37⁺⁰ to 37⁺⁶ weeks] for all birthweight centiles. The composite risk of expectant management sharply rose after [39⁺⁰ to 39⁺⁶ weeks], and was highest in infants with birthweight below the third centile ([125.2/10,000; 95% CI, 118.4–132.3]) at [40⁺⁰ to 40⁺⁶ weeks’] gestation. Balancing the risk of expectant management and delivery (neonatal mortality), the optimal delivery timing for each birthweight centile was evaluated based on relative risk differences. The rate of severe neonatal morbidity sharply decreased in the period between [37⁺⁰ to 37⁺⁶ and 38⁺⁰ to 38⁺⁶ weeks], particularly for infants with birthweight below the third centile.

The data suggested that the optimal time of birth is [37⁺⁰ to 37⁺⁶ weeks] for infants with birthweight <3rd centile and [38⁺⁰ to 38⁺⁶ weeks’] gestation for those with birthweight between the [3rd and 10th centile and >90th centile]. For all other birthweight centiles, birth from [39⁺⁰ weeks] is associated with the best outcomes. However, large numbers of planned births were required to prevent a single excess death. The healthcare costs and acceptability to women of potential universal policies of planned birth need to be carefully considered.

Source: ajog.org/article/S0002-9378(23)00282-X/fulltext