Narrowing of sex differences in infant mortality in Massachusetts

J Perinatol. 2004 Feb;24(2):94-9. doi: 10.1038/


Objectives: To examine whether the improved survival of preterm infants has influenced the known male excess in infant mortality.

Study design: We analyzed sex-specific infant mortality using linked birth and death certificates for all 619,811 live born infants in Massachusetts between 1989 and 1995.

Results: Between 1989 and 1995 the male excess in infant mortality decreased by 50%, from 1.6/1000 to 0.8/1000 live births (LB). This narrowing resulted primarily from a more rapid decline in neonatal mortality among male infants (1.5/1000 LB) than among female infants (0.9/1000 LB). The largest declines in the male excess in neonatal mortality occurred among very premature infants (GA < or = 30 weeks) and resulted primarily from a more rapid decrease in male deaths from respiratory distress syndrome.

Conclusions: The narrowing of the sex difference in mortality between 1989 and 1995 suggests that newer treatments like antenatal steroids, and surfactants may have differentially benefited male infants.

MeSH terms

  • Cause of Death
  • Female
  • Gestational Age
  • Humans
  • Infant Mortality / trends*
  • Infant, Newborn
  • Infant, Premature
  • Infant, Premature, Diseases / drug therapy
  • Infant, Premature, Diseases / mortality*
  • Male
  • Massachusetts / epidemiology
  • Regression Analysis
  • Respiratory Distress Syndrome, Newborn / mortality
  • Sex Ratio*