OBJECTIVE: Evaluate the effect of acute intrapartum stress on umbilical cord plasma levels of cholesterol, triglyceride and dehydroepiandrosterone sulphate (DS) in term infants. METHODS: Umbilical cord plasma levels of cholesterol, triglyceride and DS were measured in 176 infants that delivered >or=37 weeks' gestation. Eighty-eight infants experienced acute intrapartum stress while the remaining infants were non-stressed controls who were case-matched by gestational age and delivery method. RESULTS: The umbilical cord plasma levels of cholesterol in the stressed infants (71.7 +/- 16.1 mg/dL, mean +/- SD) were similar to those of the control infants (70.9 +/- 16.0 mg/dL). Triglyceride levels in stressed infants were significantly higher (p = 0.003) than those of control infants. Both stressed and control infants with increased triglyceride levels had normal DS levels; however, those with increased cholesterol levels had reduced umbilical cord plasma levels of DS. Stressed infants with increased cholesterol levels had significantly lower DS levels than control infants (p = 0.008). CONCLUSIONS: Intrapartum stress leads to increased fetal plasma levels of triglycerides; yet, cholesterol levels are usually unaffected. Infants with increased cholesterol levels also have reduced DS levels, suggesting that the rise in cholesterol was due to a reduction in fetal adrenal utilisation of plasma cholesterol as substrate for steroid formation.