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.