Serum immunoactive inhibin levels in early pregnancy after in vitro fertilization and embryo transfer.

Objective: To determine the maternal serum concentrations of inhibin, E2, P, and hCG in early pregnancies arising from IVF and ET or GIFT and to assess the value of these hormone measurements in determining outcome of pregnancy.

Design: Serum immunoactive inhibin, E2, P, and hCG levels were measured in the first trimester of pregnancies after IVF-ET and GIFT procedures.

Setting: In vitro fertilization and ET or GIFT was undertaken at Monash IVF, Melbourne, Victoria, Australia.

Patients: At least two blood samples were collected from 117 women between 4 and 11 weeks of gestation.

Main Outcome Measures: The hormone concentrations in the IVF-ET and GIFT pregnancies were compared with those in pregnancies and related to outcome of pregnancy.

Results: Serum inhibin levels in singleton pregnancies were significantly higher than in comparable normal pregnancies. In contrast to normal conceptions in which inhibin concentrations rose to peak at 11 weeks, the levels found in IVF-ET and GIFT singleton pregnancies were high at 5 weeks' gestation and declined subsequently. In twin pregnancies, the inhibin levels were significantly greater than those in singleton pregnancies. In biochemical pregnancies diagnosed by increasing hCG concentrations in the absence of an embryonic sac, inhibin levels were significantly lower than those found in singleton pregnancy, as were E2, P, and hCG levels. In anembryonic pregnancies, diagnosed by the confirmation of an intrauterine gestation sac with no evidence of a fetal complex, inhibin concentrations were highest at week 4 and declined, being significantly lower at all stages of gestation. In ectopic pregnancy, serum inhibin levels were lower at all stages of gestation, whereas E2 concentrations were not lower until 6 weeks and P levels until week 5. Serum hCG levels were significantly lower at all stages of gestation. In women with spontaneous abortions, inhibin levels were lower than singleton pregnancies at 7 weeks.

Conclusions: Serum inhibin concentrations are elevated in pregnancies arising from ovarian hyperstimulation in the first trimester when compared with those in normal pregnancy, probably as a result of the presence of multiple corpora lutea resulting from ovarian hyperstimulation. Serum inhibin, E2, P, and hCG are useful markers of abnormal pregnancy outcome.