The impact of advanced maternal age on the risk of perineal and anal sphincter injuries in nulliparous women.

OBJECTIVE

The aim of the present study was to determine whether advanced maternal age is associated with increased risk of perineal injury and obstetric anal sphincter injury (OASI) among primiparous women.

METHODS

This was a retrospective cohort study of primiparous women aged 20-50 years with singleton term pregnancies in cephalic presentation who delivered vaginally at a single tertiary center between 2012 and 2024. Women were stratified into three groups: 20-30 (reference), 30-40, and 40-50 years. The primary outcome was overall perineal injury, defined as spontaneous perineal laceration, labial tear, episiotomy, or OASI. The secondary outcome was OASI, analyzed separately. Multivariable logistic regression assessed the association between maternal age and each outcome.

RESULTS

Among 45 021 primiparous women, 18 230 (40.5%) were aged 20-30 years, 25 520 (56.7%) aged 30-40 years, and 1271 (2.8%) aged 40-50 years. Overall perineal injury rates were similar across groups (86.0%, 85.0%, and 85.3%), and the only significant pairwise difference was between women aged 20-30 and 30-40 years (P = 0.008). OASI rates were consistently low (0.8%, 0.9%, and 0.7%; P = 0.589). In multivariable analysis, women aged 30-40 years had lower odds of overall perineal injury compared with the reference group (adjusted odds ratio [aOR] 0.89; 95% confidence interval [CI]: 0.84-0.95; P < 0.001), whereas women aged 40-50 years showed no significant difference (aOR 0.92; 95% CI: 0.76-1.11; P = 0.371). In the model for the secondary outcome, maternal age was not associated with OASI.

CONCLUSION

Advanced maternal age is not an independent predictor of perineal injury or OASI. Clinical counseling should emphasize modifiable risk factors rather than maternal age.