Age at first birth and risk of urinary incontinence after delivery: a dose–response meta-analysis

Studies investigating the impact of age at first birth on urinary incontinence after delivery have reached inconsistent conclusions. We performed this systematic review and meta-analysis of studies assessing the risk of urinary incontinence after delivery, regardless of the type, with age at first birth. MEDLINE via PubMed and Web of science databases were searched up to March 13, 2021. Restricted cubic splines were used to model the dose–response association. Twelve publications were included in this meta-analysis. The summary odds ratio (OR) and 95% confidence interval (CI) per 1-year increase in age at first birth were 1.01 (95% CI (0.99, 1.02)) for urinary incontinence (America: 1.00 (0.99, 1.00); Europe: 1.03 (1.00, 1.06); Asian: 0.99 (0.89, 1.10)). A non-linear dose–response (P(nonlinearity) < 0.01) indicated that age at first birth older than 32 (P < 0.05) increases the risk of urinary incontinence. First birth before age 32 make decrease the risk of urinary incontinence after delivery.