Association Between Duration of Breastfeeding and Maternal Hypertension: A Systematic Review and Meta-Analysis.

OBJECTIVES: Recently, an increasing number of studies have implied that breastfeeding has a protective effect on maternal hypertension, but it remains controversial. The aim of this study is to evaluate the effect of breastfeeding on maternal hypertension through meta-analysis.

MATERIALS AND METHODS: Eligible studies were searched and identified in various databases. Meta-analysis was conducted to assess the association between the duration of breastfeeding and maternal hypertension.

RESULTS: Seven eligible studies that contained 444,759 participants were included in our study. Meta-analysis of these seven studies showed a significant protective effect of breastfeeding on maternal hypertension. Specifically, pooled odds ratios (ORs) of hypertension for >0-6, >6-12, and >12 months of breastfeeding were 0.92 (95% confidence interval [CI]: 0.88-0.96, I2  = 67.5%), 0.89 (95% CI: 0.86-0.92, I2  = 0), and 0.88 (95% CI: 0.84-0.93, I2  = 43.9%), respectively, compared with nonbreastfeeding mothers, and the pooled OR of hypertension was 0.93 (95% CI: 0.91-0.95, I2  = 40.8%) for women who breastfed compared with women who had not. Furthermore, the pooled hazard ratio of hypertension was 1.34 (95% CI: 1.17-1.52, I2  = 58.7%) for women who did not breastfeed compared with women who breastfed for more than 12 months for their first child.

CONCLUSION: Different durations of breastfeeding have different protective effects against the development of maternal hypertension, and breastfeeding for >12 months has a better effect than <12 months.