Apgar score and risk of cause-specific infant mortality

The 5-minute Apgar score and childhood school outcomes

AIM

To examine the association between Apgar score at 5 min and childhood developmental and educational outcome.

METHODS

A population-based data linkage study of births ≥37 weeks' gestation linked to developmental outcomes at preparatory school and educational outcomes at school grades 3, 5 and 7 in Victoria, Australia. Multivariable logistic regressions and generalised estimating equations were used.

RESULTS

There were 167,126 singleton infants with developmental results and 392,933 singleton infants with at least one educational result. There was an inverse relationship between Apgar score at 5 min and poor developmental and educational outcomes, with the worst outcomes among Apgar scores of 0-3. Apgar scores of 7, 8 and 9 were all associated with poorer developmental outcomes (aOR = 1.31, 95% CI: 1.12-1.54; aOR = 1.17, 95% CI: 1.05-1.29; aOR = 1.08, 95% CI: 1.02-1.13 respectively), while Apgar scores of 7 and 8 were associated with poorer educational outcomes at grades 3, 5, and 7. With progression through grades 3, 5, and 7, the extent of the difference in educational outcomes diminished (e.g. for Apgar scores of 0-3: aOR = 3.33, 95% CI: 1.85-6.00 in grade 3 and aOR = 1.49, 95% CI: 0.75-2.96 in grade 7).

CONCLUSION

Apgar scores below 10 at 5 min are associated with poorer developmental and educational outcomes in school.

Pre- and Perinatal Characteristics Associated with Apgar Scores in a Review and in a New Study of Dutch Twins

A literature review was carried out to identify pre and perinatal characteristics associated with variation in Apgar scores in population-based studies. The parameters identified in the literature search were included in the classical twin design study to estimate effects of pre and perinatal factors shared and nonshared by twins and to test for a contribution of genetic factors in 1- and 5-min Apgar scores in a large sample of Dutch monozygotic (MZ) and dizygotic (DZ) twins. The sample included MZ and DZ twins (N = 5181 pairs) recruited by the Netherlands Twin Register shortly after birth, with data on prenatal characteristics and Apgar scores at first and/or fifth minutes. The ordinal regression and structural equation modeling were used to analyze the effects of characteristics identified in the literature review and to estimate genetic and nongenetic variance components. The literature review identified 63 papers. Consistent with the review, we observed statistically significant effects of birth order, zygosity and gestational age (GA) for 1- and 5-min Apgar scores of both twins. Apgar scores are higher in first-born versus second-born twins and DZ first-born versus MZ first-born twins. Birth weight had an effect on the 5-min Apgar of the first born. Fetal presentation and mode of delivery had different effects on Apgar scores of first- and second-born twins. Parental characteristics and chorionicity did not have significant main effects on Apgar scores. The MZ twins' Apgar correlations equaled the DZ Apgar correlations. Our analyses suggest that individual differences in 1- and 5-min Apgar scores are attributable to shared and nonshared pre and perinatal factors, but not to genotypic factors of the newborns. The main predictors of Apgar scores are birth order, zygosity, GA, birth weight, mode of delivery and fetal presentation.

Comparison of the Combined versus Conventional Apgar Scores in Predicting Adverse Neonatal Outcomes

Objectives

Assessing the value of the Combined-Apgar score in predicting neonatal mortality and morbidity compared to the Conventional-Apgar.

Methods

This prospective cohort study evaluated 942 neonates (166 very preterm, 233 near term, and 543 term) admitted to a tertiary referral hospital. At 1- and 5-minutes after delivery, the Conventional and Combined Apgar scores were recorded. The neonates were followed, and the following information was recorded: the occurrence of severe hyperbilirubinemia requiring medical intervention, the requirement for mechanical ventilation, the occurrence of intraventricular hemorrhage (IVH), and neonatal mortality.

Results

Before adjusting for the potential confounders, a low Conventional (<7) or Combined (<10) Apgar score at 5-minutes was associated with adverse neonatal outcomes. However, after adjustment for the gestational age, birth weight and the requirement for neonatal resuscitation in the delivery room, a depressed 5-minute Conventional-Apgar score lost its significant associations with all the measured adverse outcomes; after the adjustments, a low 5-minute Combined-Apgar score remained significantly associated with the requirement for mechanical ventilation (OR,18.61; 95%CI,6.75–51.29), IVH (OR,4.8; 95%CI,1.91–12.01), and neonatal mortality (OR,20.22; 95%CI,4.22–96.88). Additionally, using Receiver Operating Characteristics (ROC) curves, the area under the curve was higher for the Combined-Apgar than the Conventional-Apgar for the prediction of neonatal mortality and the measured morbidities among all the admitted neonates and their gestational age subgroups.

Conclusions

The newly proposed Combined-Apgar score can be a good predictor of neonatal mortality and morbidity in the admitted neonates, regardless of their gestational age and resuscitation status. It is also superior to the Conventional-Apgar in predicting adverse neonatal outcomes in very preterm, near term and term neonates.