Secular changes of the sex-ratio of stillbirths and early deaths in Italy: evidence for postponement of male specific risk.

Abstract

Analyses of Vital Statistics from various industrialized countries have shown recent reduction of both the rate and sex-ratio of stillbirths. Two alternate explanations are conceivable for the finding: 1) the improvement of environmental conditions has actually reduced the male relative risk, 2) such an improvement has merely postponed late fetal mortality into early periods of extrauterine life. In order to discriminate between these two possibilities, both the secular trends of the sex-ratio of stillbirths and deaths in early infancy were analysed using Italian Vital Statistics. The results can be summarized as follows: 1) the sex-ratio of stillbirths continuously decreased during the examined period, from 1863 to 1979; 2) the sex-ratio of early deaths decreased until about 1920 and thereafter sharply increased. Therefore, Italian data seem to support the hypothesis of a postponement of late fetal deaths into early infant period.