Maternal serum inhibin A concentrations in early pregnancy after IVF and embryo transfer reflect the corpus luteum contribution and pregnancy outcome.

To compare maternal serum inhibin A concentrations in early pregnancy with pregnancy outcomes and treatment protocols, serum samples were collected from 237 women undergoing in-vitro fertilization (IVF) and embryo transfer cycles. Samples were collected on day 16 after oocyte retrieval for beta human chorionic gonadotrophin (HCG) pregnancy testing and inhibin A measurement. The samples were divided into non-pregnant (n = 128) and pregnant (n = 109) groups, the pregnancies were followed and outcomes determined. Inhibin A concentrations were significantly lower in non-pregnant women than in women with ongoing pregnancies (P: < 0.001) and those resulting in spontaneous abortions (P: < 0.001). In ongoing pregnancies, inhibin A concentrations were significantly lower in the absence of functioning ovaries (donor oocyte/embryo) (P: < 0.01) and in natural cycles (frozen-thawed embryo transfer) (P: < 0.01) compared with concentrations after ovarian stimulation. Further, since inhibin A concentrations were not significantly different between singleton and multiple pregnancies in the ovarian stimulation protocol, the size of the early trophoblast does not appear to influence the secretion of inhibin A. These data strongly support the concept that the corpus luteum is a major source of circulating inhibin A in early pregnancy. Additionally, low concentrations of serum inhibin A may be useful in predicting betaHCG-positive preclinical 'biochemical' pregnancies.