The association between selenium levels and hypertensive disorders of pregnancy: a systematic review of literature.

Selenium (Se) is essential for selenoprotein synthesis, being thus important for immune and thyroid function, and for antioxidant defence. Some studies have shown that low levels of Se may associate with Hypertensive Disorders of Pregnancy (HDPs). Nevertheless, evidence supporting Se supplementation in pregnant or childbearing-age women is still lacking. In this context, this work aimed to systematically review the most recent scientific evidence to understand the relationship between Se levels and HDPs. We performed a systematic review (protocol number: CRD42022310424) with literature of the last decade. PubMed, Scopus, Web of Science, registers, and grey literature were searched to identify studies reporting measurement of Se levels in normotensive and hypertensive pregnant women (supplemented or not with Se). Study quality was assessed using the National Heart, Lung, and Blood Pressure Institute Study Quality Assessment Tools. Among the 30 included studies, a majority, 61% (n=19) of the "good" or "fair" studies, reported a negative association between Se and HDPs, and some studies, 39% (n=11) of the "good" or "fair" studies, reported a lack of association. This review provides an important amount of quality evidence suggesting that low selenium levels associate with the occurrence of HDPs. Nevertheless, the gathered information is not enough to underlie a recommendation for Se supplementation in pregnancy to protect against HDPs. Thus, this review emphasizes the need for further well-designed randomized controlled trials that may provide blunt evidence regarding the benefits of Se supplementation during pregnancy.