Ethnic differneces in twinning rates in Nigeria

Abstract

A study was made of twinning rates in mothers of different ethnic origin delivered in two hospitals in Ibadan, Nigeria; the great majority were of Western Nigerian origin. The twinning rates in mothers of Western, Eastern, Mid-Western and Northern Nigerian origin were 45, 45, 31 and 21/1000 maternities, respectively. The monozygotic twinning rates determined by sex, placentation, blood groups and other genetically determined markers in the different ethnic groups varied very little, the differences in the overall twinning rates being mainly due to variation in the dizygotic rates. The effect of factors such as hospital selection and maternal age and parity on the observed incidence of twinning is discussed.