Midtrimester maternal serum inhibin A levels after multifetal pregnancy reduction

Objective: To investigate the relationship between the maternal serum inhibin A concentrations and the number of fetuses. Further, the maternal serum inhibin A levels for twin pregnancies and multiple pregnancies reduced to twins in the second trimester were compared. Methods: Three groups of women with pregnancies following in vitro fertilization and embryo transfer were recruited for this study. Groups 1, 2 and 3 included 20 singleton pregnancies, 37 twin pregnancies, and 35 multifetal pregnancies, respectively. In group 3, multifetal reduction was performed during 10-12 weeks of gestation. Blood samples were obtained longitudinally at 10th, 12th, 15th and 18th week of gestation. Results: There was a significant association between the number of fetuses and maternal plasma inhibin A prior to multifetal reduction. The inhibin A levels were not significantly different between twin and multifetal reduced twin pregnancies at 15th and 18th weeks of gestation. Conclusion: In multifetal reduction to twin pregnancies, the maternal serum levels of inhibin A decrease to the level of twin pregnancies during the second trimester. Therefore, inhibin A may be effectively used as a marker for Down syndrome screening in cases of twin pregnancy following multifetal reduction.