Impact of race on male predisposition to birth asphyxia

To examine the associations of: (a) neonatal sex with mild-to-moderate and severe birth asphyxia, (b) fetal sex with mortality due to birth asphyxia and (c) neonatal race with severe birth asphyxia.

We used the Nationwide Inpatient Sample (NIS) Database including the years 1993 to 2008 or its pediatric sub portion Kid's Inpatient Database (KID) for the years 1997, 2000, 2003 and 2006. NIS database is collected annually from more than 1000 hospitals across the United States for millions of inpatient discharge summaries. We included newborns older than 36 weeks gestational age or more than 2500 g at birth. We excluded newborns with congenital heart disease, major congenital anomalies and chromosomal disorders. We compared birth asphyxia in males to females, and in each race compared with whites, and examined effect of sex in association with birth asphyxia within each race/ethnicity.

There were 9 708 251 term infants (51.8% males) included in the study. There were 15 569 newborns diagnosed with severe birth asphyxia (1.6 in 1000); of them 56.1% were males. Odds ratio (OR)to have severe birth asphyxia in male newborns was 1.16 (confidence interval (CI): 1.12 to 1.20, P<0.001). Compared with Whites, African-American newborns had more birth asphyxia, OR 1.23 (CI: 1.16 to 1.31, P<0001), whereas Hispanics and Asians had less birth asphyxia. Native American newborns did not differ from their white counterparts. On comparing males to females within each race, male sex was associated with increased birth asphyxia in all races but Native American.

Male sex and African-American race were associated with increased prevalence of birth asphyxia.