Ruder A
Am J Hum Genet. 1985 Mar;37(2):362-72.
Because of conflicting results in previous analyses of possible maternal and paternal effects on the variation in sex ratio at birth, records of United States live births in 1975 were sorted by offspring sex, live birth order (based on maternal parity), parental races, and, unlike prior studies, ungrouped parental ages. Linear regression and logistic analysis showed significant effects of birth order and paternal age on sex ratio in the white race data (1.67 million births; 10,219 different combinations of independent variables). Contrary to previous reported results, the paternal-age effect cannot be ascribed wholly to the high correlation between paternal age and birth order as maternal age, even more highly correlated with birth order, does not account for a significant additional reduction in sex-ratio variation over that accounted for by birth order alone.
由于先前对可能存在的父母因素对出生性别比变化的影响分析结果相互矛盾,1975年美国活产记录按子女性别、活产顺序(基于母亲生育次数)、父母种族进行了分类,并且与先前研究不同的是,还按父母年龄未分组进行了分类。线性回归和逻辑分析表明,在白人种族数据(167万例出生;10219种不同的自变量组合)中,出生顺序和父亲年龄对性别比有显著影响。与先前报道的结果相反,父亲年龄效应不能完全归因于父亲年龄与出生顺序之间的高度相关性,因为母亲年龄与出生顺序的相关性更高,但它并不能单独解释出生顺序所导致的性别比变化的显著额外降低。