A systematic review examining the association between parity and gravidity & hypertension and blood pressure.

Parity and gravidity have been shown to be associated with hypertension and changes in blood pressure, but results are conflicting. We aimed to estimate the association between gravidity and parity with hypertension and blood pressure. A systematic search of multiple databases was performed. Studies were included if they reported on parity or gravidity and hypertension or blood pressure. Study characteristics were extracted and estimates were pooled using random-effects meta-analysis. A meta-analysis of 18 studies demonstrated that parity was associated with greater odds of hypertension (pooled OR = 1.31;95%CI:1.14,1.50;I2 = 90.4%) when compared to nulliparity. There was no significant difference in odds of hypertension at a parity of 1 or 2; at a parity of 3 and 4, odds of hypertension were significantly higher when compared to nulliparity. Results suggest that parity is associated with hypertension risk in a graded manner, however, there was high heterogeneity. The mechanism remains unknown but is likely multifactorial.