We consider the effects of major prenatal economic shocks experienced by mothers on two indicatorsof newborn-infant health, birth weight and head circumference, using detailed microdata from the UKALSPAC survey. Controlling for physiological and socioeconomic factors, an economic shock in the first18 weeks of gestation lowers birth weight by 40-70 grams and head circumference by 2-3mm. We findevidence of transmission via poorer maternal health due to absolute material deprivation and tobaccoand alcohol consumption, but not for the endocrinological effects of increased psychosocial anxiety. Thefragile-male hypothesis holds for birth weight but not for head circumference, as predicted by recenttheories on gender differences in prenatal development.