Abstract
BACKGROUND: Researchers have shown that diet is associated with hypertensive disorders of pregnancy, and there are some reports of performed meta-analyses on observational studies. However, very few randomized-controlled trials have systematically summarized. Thus, we reviewed and meta-analyzed the effects of nutritional interventions on risks of gestational hypertension (GH) or/and preeclampsia (PE). MATERIALS AND METHODS: A systematic search was performed using Medline, Cochrane library, Google Scholar, ISI Web of Science, Scopus, and ProQuest to find randomized clinical trials assessing the effect of nutritional interventions on incidences of GH or/and PE compared to control or placebo interventions. RESULTS: After considering duplicates, 1066 articles were screened from the database searches. Full-text articles were retrieved for 116 records, while 87 did not have the inclusion criteria and were later omitted. Twenty-nine studies were eligible, but 8 studies were not included in the meta-analysis due to insufficient data. Finally, seven studies were included in qualitative analysis. Furthermore, 7 studies (693 in intervention vs. 721 in control) were pooled for managed nutritional interventions, three (1255 vs. 1257) for a Mediterranean-style diet, and 4 (409 vs. 312) for sodium restricted. Our results revealed that managed nutritional programs were effective in reducing the incidence of GH (odds ratio [OR] = 0.37; 95% confidence interval [CI] = 0.15, 0.92); I(2) = 66.9%; P = 0.010), but not for PE (OR = 0.50; 95% CI = 0.23, 1.07); I(2) = 58.9%; P = 0.032. The Mediterranean-style diets in three trials (1255 vs. 1257) did not reduce the risk of PE (OR = 1.10; 95% CI = 0.71, 1.70); I(2) = 2.3%; P = 0.359). Likewise, sodium-restricted interventions in four trials (409 vs. 312) did not decrease total risk of GH (OR = 0.99; 95% CI = 0.68, 1.45); I(2) = 0%; P = 0.520). Meta-regression did not indicate any significant association between maternal age, body mass index, gestational weight gain, and start time of all interventions with the incidence of GH or/and PE (P > 0.05). CONCLUSION: The present meta-analysis showed that Mediterranean-style diets and sodium-restriction interventions did not decrease the incidence of GH or/and PE in healthy pregnancies; however, managed nutritional programs reduced the risk of GH, the total incidence of GH and PE, but not PE.