title: Seasonality in the sex ratio of US black births.
abstract: It is shown that the seasonality of sex ratio in US Black births in synchronous with that of US White births. This seasonality is comparable with that of dizygotic twin births and of the births of boys with undescended testes. These comparisons are consistent with the hypothesis that the sex of an infant is partially controlled by the maternal gonadotrophin levels at the time of its conception.
mesh_terms: D044383:Black People; D004812:Epidemiologic Methods; D005260:Female; D006062:Gonadotropins / Q000097:blood; D006801:Humans; D008297:Male; D011247:Pregnancy; D012621:Seasons; D012744:Sex Ratio; D014481:United States; D001741:Black or African American
chemical_list: D006062:Gonadotropins