Maternal waist-to-hip ratio does not predict child gender

It has been suggested that a high pre-conceptual waist-to-hip ratio (WHR) is a good predictor of male offspring and, thus, in cultures that value male children, an androgenous body shape may be judged as most attractive. The predictive value of WHRs is based on studies measuring women who already have children and correlating their WHRs with the proportion of existing male offspring. However, carrying a male child may alter WHRs in a different way to carrying a female child, and a high WHR may be an effect rather than a cause of male offspring. In order to test the predictive power of a pre-conceptual WHR and offspring gender, we took WHR measures from 458 women who intended to become pregnant and then correlated this with the genders of their subsequent children. We found no significant correlation. It is therefore not clear why a high WHR is preferred in some cultures. We suggest that differences in attractiveness preferences between different ethic groups are actually based on weight scaled for height (the body mass index or BMI) rather than the WHR since although there will be a preferred optimal BMI for each ethnic group, which will balance environmental and health factors, this optimal BMI may differ between groups and environments.