Apgar scores of 7 to 9 tied to increased risks of neonatal mortality, morbidity
Infants with low Apgar scores within the normal range (7–10) are at increased risks of neonatal mortality and morbidity, according to a study in Sweden. Compared with infants with stable Apgar scores of 10, those with a decrease in score from 5–10 minutes are also at higher risk of morbidity.
“Our findings provide strong evidence to support the proposition that the optimal Apgar score is 10 at each time point, and all newborns should be assigned an Apgar score at 10 minutes, regardless of their score at 1 minute and 5 minutes,” researchers said.
This population-based cohort study included 1,551,436 nonmalformed live singleton infants, born at term (≥37 weeks’ gestation) between 1999 and 2016, with Apgar scores of ≥7 at 1, 5 and 10 minutes. Infants with Apgar scores of 7, 8 and 9 were compared with those with an Apgar score of 10 at each time point.
The primary endpoints were neonatal mortality and morbidity, including neonatal infections, asphyxia-related complications, respiratory distress and neonatal hypoglycaemia. Researchers estimated adjusted odds ratios (aOR), adjusted rate differences (aRD) and 95 percent confidence intervals (CIs).
Infants with lower Apgar scores, particularly at 5 and 10 minutes, had higher aORs for neonatal mortality, neonatal infections, asphyxia-related complications, respiratory distress and neonatal hypoglycaemia than those with an Apgar score of 10. Case in point, infants with an Apgar score of 9 vs 10 had aORs for respiratory distress of 2.0 (95 percent CI, 1.9–2.1) at 1 minute, 5.2 (5.1–5.4) at 5 minutes and 12.4 (12.0–12.9) at 10 minutes. [BMJ 2019;365:l1656]
The aRDs for respiratory distress were 9.5 percent (9.2–9.9 percent) and 41.9 percent (37.7–46.4 percent) for infants with an Apgar score of 9 and 7 at 10 minutes, respectively, compared with those with an Apgar scores of 10 at 10 minutes. In addition, infants who experienced a reduction in Apgar score from 10 at 5 minutes to 9 at 10 minutes had a higher risk of neonatal morbidity than those with a stable Apgar score of 10 at 5 and 10 minutes.
In earlier studies, Apgar score <7 correlated with neonatal morbidity, including meconium aspiration, neonatal respiratory distress, hypoxic-ischaemic encephalopathy and infant mortality. Such association was attributed to anoxia or infections. [Lancet 2014;384:1749-1755; Obstet Gynecol 2001;98:65-70; Rev Assoc Med Bras (1992) 2012;58:587-593; Eur J Obstet Gynecol Reprod Biol 2017;210:251-256]
“Our study expands on these findings by showing that even ‘normal’ Apgar scores (7 to 9) are strongly associated with higher risks of neonatal mortality and neonatal morbidity, and neonatal morbidity is associated with risks of long-term neurological disorders,” researchers said. [Epilepsia 1984;25:131-136]
These results support those of a previous study, which suggest that adverse outcomes are frequent in some acidaemic infants with normal Apgar scores within the normal range (7–9). [Am J Obstet Gynecol 2016;215:486]
“The strong relations between Apgar scores of 7, 8 and 9 and neonatal morbidity, and the associations between pregnancy complications and lower Apgar scores in the normal range observed in our study, provide insight into previous findings of increased risks of cerebral palsy, epilepsy, autism and adverse developmental outcomes in children with Apgar scores of 7, 8 and even 9, compared with an Apgar score of 10,” researchers said. [Eur J Epidemiol 2019;34:105-114; Eur J Epidemiol 2016;31:125-136]