Association between apgar score at 5 minutes and adverse outcomes among Low-Risk pregnancies

Abstract

Objective Among low-risk pregnancies, we aimed to ascertain the association between 5-minute Apgar score and adverse outcomes of newborn-maternal dyad. Study design We conducted a retrospective cohort study using the U.S. vital statistics datasets (2012–2016), including live births from low-risk women with non-anomalous singleton gestations who delivered at 37–41 weeks. Apgar score was categorized as low (0–3), moderate (4–6), and normal (7–10). The primary outcome was composite neonatal adverse outcome (any of the following: assisted ventilation > 6 h, neonatal seizure, or neonatal death). The secondary outcomes were infant mortality and composite maternal adverse outcome (any of the following: admission to the intensive care unit, blood transfusion, uterine rupture, or unplanned hysterectomy). Multivariable Poisson regression analyses were used to estimate the association between 5-minute Apgar score and adverse outcomes (using adjusted relative risk [aRR] and 95% confidence intervals [CI]). Results Of 19.9 million live births delivered between 2012 and 2016, 11.7 million (58.7%) met inclusion criteria; 98.9% had a normal 5-minute Apgar score, 0.9% had a moderate score, and 0.2% had a low score. The overall composite neonatal adverse outcome was 3.2 per 1,000 live births and the rates were significantly higher among those with a moderate (aRR 20.8; 95% CI 20.2–21.4) or low score (aRR 43.1; 95% CI 41.6–44.5) than normal score. The overall composite maternal adverse outcome was 2.45 per 1,000 live births and it was significantly higher in deliveries with a moderate (aRR 3.1; 95% CI 2.9–3.3) and low (aRR 4.6; 95% CI 4.2–5.0) 5-minute Apgar score than those with a normal score. Infant mortality also showed a similar pattern. Conclusion Though approximate 1% of live births had a 5-minute Apgar score below 7 among low-risk pregnancies, a decreased score was associated with a significantly higher risk of neonatal and maternal adverse outcomes, as well as infant mortality.