Are observed associations between a high maternal prepregnancy body mass index and offspring IQ likely to be causal?

A high maternal prepregnancy body mass index has been associated with lower offspring IQ, but it is unclear if the relationship is causal. To explore this, our objectives were to compare maternal and paternal estimates and to assess whether certain factors mediate the association.We analysed data from the Avon Longitudinal Study of Parents and Children, which initially recruited 14 541 women residing in Avon, UK, with an expected date of...