In Reply We thank Jha et al and Aubin et al for their interest in our Original Investigation.1 Jha and colleagues speculate that the association of low fetal growth with depression might be stronger among female individuals. To test this hypothesis, we stratified by sex and regressed depression onto the clinical diagnosis small for gestational age within sibling pairs. Although the results were not statistically significant, they are in the hypothesized direction (male probit: β = 0.009, SE = 0.044 and female probit: β = 0.067, SE = 0.035). While this is an interesting hypothesis, we remain agnostic about its veracity given that the difference is not statistically significant and that it is unclear if the association remains after partialling out what depression shares with all other disorders.