Genetic effect on Apgar score

Intraclass correlation coefficients for one- and five-min Apgar scores of 6 04 twin pairs born at a southeastern Brazilian hospital were calculated, af ter adjusting these scores for gestational age and sex. The data support a genetic hypothesis only for 1-min Apgar score, probably because it is less affected by the environment than 4 min later, after the newborns have been under the care of a neonatology team. First-born twins exhibited, on averag e, better clinical conditions than second-born twins. The former showed a s ignificantly lower proportion of Apgar scores under seven than second-born twins, both at 1 min (17.5% vs. 29.8%) and at 5 min (7.2% vs. 11.9%). The p roportion of children born with "good" Apgar scores was significantly small er among twins than among 1,522 singletons born at the same hospital. Among the latter, 1- and 5-min Apgar scores under seven were exhibited by 9.2% a nd 3.4% newborns, respectively.