Sex ratio of live births in south-western Nigeria.

Among European and North American whites, the proportion of males among live births is about 51.4%, while among negroes in the United States the figure is 50.7%. To test the correctness of the common assumption that the proportion among Africans is the same as that for negroes in the United States, records over seven years for Yorubas of south-western Nigeria have been examined. Among 548 558 hospital live births the male proportion was 51.37%, while vital registration records for one urban and one rural town showed a figure of 51.39% in 315 735 live births. Of the total 864 331 live births, the overall proportion was 51.4 +/- 0.05%, significantly higher than the 50.7% for American negroes.