Serum levels of müllerian inhibiting substance in preterm and term male neonates

PURPOSE: Müllerian inhibiting substance, also called anti-müllerian hormone, is responsible in the embryo for the regression of the müllerian structures. During the second and third trimesters the physiological functions that müllerian inhibiting substance may have after the period of müllerian duct regression are poorly understood. We obtained information on müllerian inhibiting substance levels in the male newborn during this period of gestation. MATERIALS AND METHODS: Müllerian inhibiting substance was measured by an enzyme immunoassay in cord blood obtained at birth in 27 preterm (25 to 36 weeks of gestation) and 92 term (37 to 42 weeks) male neonates. RESULTS: Cord serum müllerian inhibiting substance concentrations were relatively high from 25 to 31 weeks (mean plus or minus standard deviation 86.4 +/- 36.1 ng./ml.) and then they decreased from 32 weeks to term (mean 24.2 +/- 14.0 ng./ml.). CONCLUSIONS: The decline early in the third trimester may be consistent with müllerian inhibiting substance having a function during the second but a diminished role in the third trimester.