The effect of hormones on the sex ratio of infants following artificial insemination.

Data have been reviewed on the sex ratio of infants following artificial insemination (AI). It is concluded: In cases where AI is preceded by hormone treatment the sex ratio is lower (P less than 0.002) than in cases at the same centre where there is no hormone treatment. Part of the association of sex ratio with cryostorage of semen detected by other workers seems secondary to an association of both with hormone treatment. It is not clear whether, in addition, cryostorage has an independent effect on sex ratio. AI (in the absence of hormone treatment) raises the sex ratio, apparently to different degrees in different clinics. It is noteworthy that hormone treatment in AI has the same effect as hormone treatment with natural insemination--to reduce the sex ratio. This is interpreted as evidence for the hypothesis that gonadotrophin has a pre-conceptional sex-selective effect.