Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. This population-based cohort study is the first to establish an evidence-based recommendation of delivery at 39 weeks for females with pregnancies conceived via infertility treatments and assisted reproductive technology (ART).

Evidence Rating Level: 2 (Good)

The proportion of females between the ages of 15 to 49 receiving infertility therapies has risen over recent years. Assisted reproductive technology (ART) more specifically, although useful, is also associated with the risk for low birth weight, perinatal mortality, and stillbirth. The lack of current recommendations surrounding timing of delivery in infertility-conceived pregnancies is what the current study sought to explore. This population-based retrospective cohort study analyzed data from 178,448 singleton infertility-conceived pregnancies in the US from 2014 to 2018. The study defined ‘risk of delivery’ as the collective rate of neonatal morbidity (Apgar score of ≤ 3 at 5 minutes, ventilation of ≥ 6 hours, seizure, or NICU admission) and infant death (within 1 year of life) in a gestational week per 10,000 deliveries. This was compared with the risk of delivery in the subsequent week, which included infant death and neonatal morbidity, plus the rate of stillbirths per 10,000 pregnancies in that subsequent week. Overall mortality and morbidity risk increased with advanced gestation. The rate of stillbirths per 10,000 pregnancies was lowest at 37 weeks and highest at 42 weeks gestation, a pattern observed regardless of type of infertility treatment. The rate of infant death per 10,000 live births was lowest at 39 weeks for infertility (6.2; 95% CI, 4.2-9.1) and ART-specific (5.2; 95% CI, 3.2-8.1) pregnancies. For both infertility and ART pregnancies, the overall risk of delivery at 39 weeks was significantly lower than risk of delivering in the subsequent gestational week (Infertility: 479 vs 599 per 10 000 live births; ART: 510 vs 664 per 10 000 live births). At 39 weeks, the combined mortality and morbidity relative risk (RR; 95% CIs) of delivery in the subsequent week of gestation exceeded the risk of delivering in the 39th week for both infertility (RR, 1.25; [95% CI, 1.19-1.31]) and ART (RR, 1.30; [95% CI, 1.22-1.39]). Mortality risk in infertility pregnancies was higher starting at 38 weeks gestation and later (38 weeks: RR, 1.72 [95% CI, 1.04-2.86]), whereas for ART pregnancies, this was the case at 39 weeks and later (RR, 2.24; [95% CI, 1.23-4.10]). A total of 128 infant deaths (representing 0.7% of the study population) and 248 stillbirths (representing 0.14% of the study population) were recorded. This cohort study is the first to provide comprehensive evidence for the recommendation of delivery at 39 weeks’ gestation for pregnancies conceived through infertility treatments, and findings also suggested a potentially increased risk for adverse outcomes both early-term as well as late-term in this population.

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