Fetal plasma testosterone correlates positively with cortisol.

BACKGROUND Fetal exposure to testosterone has been implicated in programming childhood behaviour, but little is known about the determinants of fetal testosterone concentrations. AIMS To investigate the relation between fetal testosterone and maternal and fetal cortisol. METHODS Clinically indicated blood samples taken from 44 human fetuses (mean gestational age 27 weeks, range 15-38), together with paired maternal samples, were analysed for testosterone and cortisol concentrations. RESULTS Male fetuses had significantly higher concentrations of testosterone than females. Female but not male fetal concentrations rose significantly with gestational age. Fetal testosterone correlated positively with both fetal cortisol and maternal testosterone concentrations. Multiple regression showed that maternal testosterone and fetal cortisol were independently correlated with fetal plasma testosterone in both sexes. CONCLUSION Unlike the norm in the adult, where testosterone production is often inhibited by cortisol, in the fetus there is a positive link between the two.