Male newborns are somewhat heavier than female ones and it has been reported, in a Caucasian population, that mothers carrying boys have higher energy intake during pregnancy compared to those carrying girls. In the context of a prospective study comprising 150 Caucasian women in Boston, USA and 243 Asian women in Shanghai China, energy intake at the second trimester of pregnancy was estimated based on center-specific food frequency questionnaires. There was a significant interaction (P = 0.01) of maternal height with offspring gender with respect to maternal daily energy intake. Among taller women, male gender of the offspring was associated with higher maternal energy intake (difference 341 kcal/day, 95% Confidence Interval 77-604; P = 0.01), whereas among shorter women, no significant association existed between offspring gender and maternal daily energy intake (difference -213 kcal/day, 95% Confidence Interval -479 to 54; P = 0.12). Our findings indicate that the higher somatic growth potential of boys in intrauterine life is realized only when there are no constrains imposed by maternal anthropometry and it is, then, associated with higher maternal energy intake during pregnancy.