The sex ratio of Oriental births.

It has been hypothesized that high maternal gonadotrophin levels at the time of conception are causally associated with subsequent births of female infants. Dizygotic (DZ) twinning rates correlate positively with maternal gonadotrophin level. Hence, if the hypothesis were correct, DZ twinning and sex ratio should correlate negatively across other variables Oriental births have low DZ twinning rates, so if the hypothesis were true, oriental sex ratios should be high. In this report published evidence on this point is reviewed, and data on the sexes of Oriental births in the USA are examined. In general (and in conformity with the hypothesis), Oriental births seem to have higher sex ratios than white births, and in the USA, Filipino and Chinese births have significantly higher sex ratios than white births. But the USA Japanese births have a sex ratio that is non-significantly lower than the white sex ratio. Thus the bulk of data on the point seem to support the hypothesis, but there are exceptions.