Circulating Pregnancy Hormone Relaxin as a First Trimester Biomarker for Preeclampsia

Abstract Objective Preeclampsia, a multi-system hypertensive disorder, is associated with perturbations in the maternal cardiovascular system during early pregnancy. The corpus luteal hormone relaxin, a potent vasodilator, may contribute to physiological circulatory changes especially in early gestation when circulating levels are highest. This study investigated whether first trimester circulating relaxin may be a suitable biomarker for the early prediction of preeclampsia. Methods Relaxin was initially measured in first-trimester samples of women who developed late-onset preeclamptic (LO-PE; delivery ≥34 weeks; n=33) and uncomplicated pregnancies (n=25) in Pittsburgh, USA. Subsequently, to expand the group numbers, relaxin was measured in women who developed LO-PE (n=95), early-onset preeclamptic (EO-PE; delivery Results In the Pittsburgh subjects, low relaxin levels (lowest centile: Conclusion Relaxin shows little improvement in the performance of first trimester prediction models, which does not support its clinical implementation as a biomarker. Although this study was only correlational, the results point to a possible pathophysiologic role for low relaxin levels in pregnancies that later develop LO-PE.