Sex differentials in perinatal mortality in China and Finland

This study describes patterns of sex differentials in perinatal mortality in China and Finland. The analysis is based on three population-based one-year birth cohorts, one from Qingdao, China, in 1992 and two from Northern Finland in 1966 and 1985-86, comprised of 9,219, 11,422 and 9,207 singletons with at least 28 gestational weeks and 1000 g in birthweight, respectively. Both Finnish cohorts had an excess of male over female perinatal deaths, but in the Chinese cohort girls were more likely to die than boys. The adjusted odds ratio (OR) of perinatal mortality for boys was 1.31 (95 per cent confidence interval [CI] 0.98, 1.78) and 1.57 (95 per cent CI 0.89, 2.78) in the Finnish 1966 and 1985-86 cohorts, respectively, and 0.82 (95 per cent CI 0.55, 1.20) in the Chinese cohort. The corresponding figure for stillbirths in the Chinese was 0.57 (95 per cent CI 0.33, 0.98), which could explain the total excess of female deaths during the perinatal period. Our results suggest that the role of different social and cultural environments on the existing sex differentials in perinatal mortality between the countries needs further evaluation.