ABSTRACT

This study explores the short-term relationships between sex ratio at birth and late fetal mortality in Italy from 1910 to 2016. As the leading scholars’ attention traditionally focused on long-term trends and variations in the sex ratios at birth among different populations, less interest regarded short-term fluctuations as they were mainly seen as an effect of random variability. We detrended the national series of males proportion among live births and stillbirths by their medium-term component to consider the annual deviations from a normal trend. After controlling for fertility tendencies and wars effects, regression models seem to show the effects of stillbirth on the proportion of male newborns. A sensitivity analysis was also carried out to assess the effects of the perinatal deaths on the proportion of males at birth, combining stillbirths and early neonatal losses to control the possible misspecification between stillborn infants and early neonatal deaths. The significance of late fetal mortality reflects the mortality excess among male fetuses during the intrauterine life, showing evidence for the in utero hypothesis selection.

摘要

本研究探讨了 1910 年至 2016 年意大利出生性别比与晚期胎儿死亡率之间的短期关系。由于主要学者的注意力传统上集中在不同人群出生性别比的长期趋势和变化上，较少利息认为短期波动是因为它们主要被视为随机可变性的影响。我们按中期成分去除了全国男性活产和死产比例序列的趋势，以考虑与正常趋势的年度偏差。在控制生育倾向和战争影响后，回归模型似乎显示了死产对男性新生儿比例的影响。还进行了敏感性分析以评估围产期死亡对出生时男性比例的影响，结合死产和早期新生儿损失，以控制死产婴儿和早期新生儿死亡之间可能存在的错误确定。晚期胎儿死亡率的显着性反映了宫内男性胎儿死亡率过高，表明子宫内假设选择。