Antioxidants in Pregnancy: Do We Really Need More Trials?

Abstract

Human pregnancy can be affected by numerous pathologies, from those which are mild and reversible to others which are life-threatening. Among these, gestational diabetes mellitus and hypertensive disorders of pregnancy with subsequent consequences stand out. Health problems experienced by women during pregnancy and postpartum are associated with significant costs to health systems worldwide and contribute largely to maternal mortality and morbidity. Major risk factors for mothers include obesity, advanced maternal age, cardiovascular dysfunction, and endothelial damage; in these scenarios, oxidative stress plays a major role. Markers of oxidative stress can be measured in patients with preeclampsia, foetal growth restriction, and gestational diabetes mellitus, even before their clinical onset. In consequence, antioxidant supplements have been proposed as a possible therapy; however, results derived from large scale randomised clinical trials have been disappointing as no positive effects were demonstrated. This review focuses on the latest evidence on oxidative stress in pregnancy complications, their early diagnosis, and possible therapies to prevent or treat these pathologies.

Keywords: antioxidants; oxidative stress; preeclampsia; pregnancy.

Figure 1

Abnormal (top) and normal (bottom) uterine artery Doppler waveform in the first trimester. While systolic velocities are similar, the lower waveform show a low resistance vessel with broader systolic peak, as well as a continuous diastolic flow, secondary to a complete remodelling of the spiral arteries. In contrast, the abnormal waveform (up) shows an artery with high resistance, as well as a sharp systolic peak, a flow reduction at the start of diastole (“notch”), and low diastolic velocities with poor blood flow.

Figure 2

Main events in the development of preeclampsia. eNOS = endothelial nitric oxide synthase.