Analysis of multiple birth rates in Japan V. Seasonal and social class variations in twin births

SummarySeasonal variation in twin births was studied in Japan using data on 12,392 pairs of twins in 1974. The highest twinning rates per 1,000 births for MZ (4.56) and DZ (2.20) twins were seen in April, the lowest rate in September (3.69) for MZ twins and in July (1.71) for DZ twins.Occupation of the heads of the household did not affect twinning rate in… CONTINUE READING