Nutritional supplements for preventing preeclampsia: A network meta-analysis.

Research on the effects of different oral nutritional supplements in preventing preeclampsia has yielded controversial results. This network meta-analysis sought to ascertain the effect of diverse oral nutritional supplements in preventing preeclampsia. Randomised controlled trials in preventing preeclampsia were searched in PubMed, Cochrane Library, Embase, and Web of Science. The primary outcome was preeclampsia. Secondary outcomes included eclampsia and gestational hypertension. 22 studies were included, with 18133 participants in the intervention group and 17971 in the placebo group. Compared with placebo, L-arginine and vitamin B and vitamin C and vitamin E (L-arginine-VB-VC-VE) [Odds ratio (OR)=0.33, 95% confidence interval (CI) (0.20, 0.54)], linoleic-acid-calcium (OR=0.16, 95% CI 0.041, 0.50), vitamin D (VD) (OR=0. 34, 95% CI 0.17, 0.65), and calcium (OR=0.77, 95% CI 0.65, 0.91) were more effective in preventing preeclampsia. The first three nutritional supplements were superior to calcium. There was no difference among these three supplements. None of the four nutritional supplements (calcium, phytonutrient, VC, and VC-VE) were effective in preventing gestational hypertension. Oral calcium, L-arginine-VB-VC-VE, linoleic-acid-calcium, and VD could be effective approaches to prevent preeclampsia.