Prednisolone is widely used to treat medical conditions in pregnancy, despite the lack of long term safety studies on infants. Animal studies have shown that antenatal glucocorticoid treatment can cause in utero growth restriction and up-regulation of the offsprings' hypathalamic–pituitary–adrenal axis. We recruited women treated antenatally with prednisolone, and followed 12 of the infants up to four months, using routine infant vaccinations as a stressor. Birthweights were similar to controls (n= 289, uncomplicated, singleton term pregnancies), as were infants' baseline and stress-induced cortisol levels. Mothers rated their infants as less difficult and more adaptable than controls. This study provides initial reassurance about the safety of prednisolone in pregnancy.