Correlation between second trimester maternal serum inhibin-A and human chorionic gonadotrophin for the prediction of pre-eclampsia

Abstract

We aimed to investigate the relationship between inhibin-A and human chorionic gonadotrophin (hCG) concentrations in the second trimester in the same cohort of women and compare their screening efficiency for the subsequent development of pre-eclampsia. The main outcome measures were pre-eclampsia and pre-eclampsia requiring delivery before 37 weeks.We carried out a retrospective examination of inhibin-A and free beta-hCG levels taken between 15 and 19 weeks of gestation, from 685 women. The values were corrected for weight and gestation and presented as multiples of the median (MoM). Receiver operator characteristic (ROC) curves for the prediction of pre-eclampsia and pre-eclampsia requiring delivery before 37 weeks were created for both analytes alone and in combination. Based on this data the sensitivities for the prediction of pre-eclampsia using inhibin-A and hCG, alone and in combination were examined for a specificity of 90 per cent.Thirty-five (5.5 per cent) women developed pre-eclampsia, of whom 15 (2.7 per cent) required delivery before term as a result of pre-eclampsia. There was no correlation between inhibin-A and hCG for the whole population (r=0.08) but there was a significant correlation for women who subsequently developed pre-eclampsia (r=0.648) or preterm pre-eclampsia (r=0.84). For a specificity of 90 per cent the sensitivity using inhibin-A was significantly better than for hCG (48.6 per cent versus 31.4 per cent, P< 0.05). The results were similar for preterm pre-eclampsia (P< 0.05). The addition of hCG data to inhibin-A data did not improve the sensitivity for pre-eclampsia compared to inhibin-A alone (42.9 per cent versus 48.6 per cent, P< 0.20).Inhibin-A is a more sensitive marker for the subsequent development of pre-eclampsia than hCG. Addition of hCG data to inhibin-A did not improve the screening efficacy for pre-eclampsia suggesting that inhibin-A and hCG are markers of the same underlying pathological process.