Associations between low Apgar scores and mortality by race in the United States: A cohort study of 6,809,653 infants

Abstract

Background Apgar scores measure newborn health and are strongly associated with infant outcomes, but their performance has largely been determined in primarily white populations. Given the majority of the global population is not white, we aim to assess whether the association between low Apgar score and mortality in infants varies across racial groups. Methods and findings Population-based cohort study using 2016 to 2017 United States National Vital Statistics System data. The study included singleton infants born between 37+0 and 44+6 weeks to mothers over 15 years, without congenital abnormalities. We looked at 3 different mortality outcomes: (1) early neonatal mortality; (2) overall neonatal mortality; and (3) infant mortality. We used logistic regression to assess the association between Apgar score (categorized as low, intermediate, and normal) and each mortality outcome, and adjusted for gestational age, sex, maternal BMI, education, age, previous number of live births, and smoking status, and stratified these models by maternal race group (as self-reported on birth certificates). The cohort consisted of 6,809,653 infants (52.8% non-Hispanic white, 23.7% Hispanic, 13.8% non-Hispanic black, 6.6% non-Hispanic Asian, and 3.1% non-Hispanic other). A total of 6,728,829 (98.8%) infants had normal scores, 63,467 (0.9%) had intermediate scores, and 17,357 (0.3%) had low Apgar scores. Compared to infants with normal scores, low-scoring infants had increased odds of infant mortality. There was strong evidence that this association varied by race (p < 0.001) with adjusted odds ratios (AORs) of 54.4 (95% confidence interval [CI] 49.9 to 59.4) in non-Hispanic white, 70.02 (95% CI 60.8 to 80.7) in Hispanic, 23.3 (95% CI 20.3 to 26.8) in non-Hispanic black, 100.4 (95% CI 74.5 to 135.4) in non-Hispanic Asian, and 26.8 (95% CI 19.8 to 36.3) in non-Hispanic other infants. The main limitation was missing data for some variables, due to using routinely collected data. Conclusions The association between Apgar scores and mortality varies across racial groups. Low Apgar scores are associated with mortality across racial groups captured by United States (US) records, but are worse at discriminating infants at risk of mortality for black and non-Hispanic non-Asian infants than for white infants. Apgar scores are useful clinical indicators and epidemiological tools; caution is required regarding racial differences in their applicability.

Five-minute Apgar score and risk of neonatal mortality, severe neurological morbidity and severe non-neurological morbidity in term infants – an Australian population-based cohort study

“…Another strength is our inclusion of neonatal morbidity including severe neurological and non-neurological morbidity as co-primary outcomes. Previous studies 6 , 37 , 38 evaluating Apgar scores among term infants have focused mainly on neonatal and infant mortality despite the fact that neonatal morbidity occurs at a much higher rate. We also attempted to provide more granularity of information by stratifying both Apgar scores and by term gestational age categories in an attempt to show the combined effect of both on outcomes.…”

Apgar Score and Neurodevelopmental Outcomes at Age 5 Years in Infants Born Extremely Preterm

“…This study also has several limitations. Although we integrated many known risk factors, the number of documented items in the study was limited and we could not integrate information on race or ethnicity beyond foreign maternal birth or on the family context aside from maternal living situation and education and parental employment status . The low percentage of infants with Apgar scores of 0 to 3 and the restricted sample size compared with studies on preterm mortality constitute further restrictions of our analyses, but larger-scale clinical follow-up would not have been feasible .…”

Rate and determinants of low fifth minute Apgar score at the federal medical centre Yenagoa, Bayelsa State, Nigeria

“…It was 0.46% in a study done in Brazil, 0.57% in a study in Peru and 1.2% in a study in the USA. 16,17,15 This variation in rates of low fifth minute Apgar score within and across countries may reflect the varying availability, quality and utilization of antenatal and neonatal services and manpower, and preferences for elective caesarean section over labour or vaginal delivery.…”

“…The incidence of fifth minute Apgar score <7 was 1.2% in USA, 0.46% in Brazil and 0.57% in Peru. [15][16][17] Within Africa, Ethiopian studies reported rates of low fifth minute Apgar score or perinatal asphyxia ranging from 6.7% to 32%. 9,18-24 A meta-analysis of 13 studies in east and central Africa reported a pooled prevalence of 15.9%.…”

“…[29][30][31][32][33][34][35][36][37][38][39][40] A study in USA recorded 0.06%, while in China 28.72% was recorded in 2016. 15,41 Several studies have documented independent fetal/neonatal and maternal factors associated with low fifth minute Apgar score. 9,[16][17][18][19][20][21][22][23][24][26][27][28][42][43][44][45][46] No previous study has been undertaken at the Federal Medical Centre Yenagoa, Bayelsa State, Nigeria, to assess the rate of low fifth minute Apgar score and its determinants, hence the need for this study to add to the data and knowledge from south-south Nigeria.…”