First and second trimester maternal serum inhibin A levels in twins with pre-eclampsia

Objective To investigate maternal serum inhibin as a marker of pre-eclampsia (PE) in twins. Methods One hundred forty-three twins and 109 unaffected singleton pregnancies were recruited in the first trimester from the same institution. Blood samples were stored at recruitment and in the second trimester, retrospectively tested for inhibin and values expressed in multiples of the gestation-specific median (MoMs) in singletons, adjusted for maternal weight, as appropriate. Results The median inhibin level in unaffected twins was 2.04 MoM compared with 1.00 MoM in singletons (P<0.0001, Wilcoxon Rank Sum Test, one-tailed). Excluding early fetal losses the median in 22 samples from 12 twins with PE was 2.65 MoM compared with 1.99 MoM in 201 samples from 120 unaffected twins (P<0.02, Wilcoxon Rank Sum Test). This effect was restricted to second trimester samples with medians in cases and controls of 2.86 and 1.91 MoM respectively. Logistic regression of inhibin A together with established PE marker placental growth factor and placental associated plasma protein showed that in the second trimester, it improved screening performance although not reaching statistical significance (P=0.08). Conclusions Inhibin A is a potential second trimester marker of PE in twins. It may improve on existing twin screening protocols but more data are required. (C) 2016 John Wiley & Sons, Ltd.