Increase in serum concentrations of inhibin in early onset pre-eclampsia with intrauterine growth restriction

Aim: Recently, it has been hypothesized that reduced placental blood flow in early pregnancy causes changes in endothelial function, leading to pre-eclampsia. To clarify this clinically, we assessed serum concentrations of inhibin and uric acid in pre-eclamptic women compared with those of normotensive pregnant women. Methods: One hundred and forty normotensive pregnant women (at 20-41 weeks' gestation) and 50 women with pre-eclampsia (at 24-41 weeks' gestation) were the study subjects. Pre-eclamptic women were classified according to the new criteria for pregnancy-induced hypertension produced by the Japanese Society of Obstetrics and Gynecology (JSOG). Serum concentrations of uric acid and inhibin were measured enzymatically and by radioimmunoassay, respectively. Results: Serum concentrations of inhibin and uric acid in the pre-eclamptic women were significantly higher than in gestational age-matched normotensive pregnant women. There were significant correlations among inhibin and uric acid, blood pressure and birth weight. According to JSOG criteria, of the 50 pre-eclamptic women, 18 were early onset (EO), including 16 cases complicated by intrauterine growth restriction (IUGR), and 32 cases were late onset, including 12 cases complicated by IUGR. In the patients with EO and IUGR, serum concentrations of inhibin, but not uric acid, were significantly elevated as compared with those of the other pre-eclamptic women. Conclusions: The results suggest that an increase in the serum concentration of inhibin seen in EO pre-eclampsia, together with IUGR, might be a cause of reduced placental blood flow.