Predictors of severe perineal lacerations in Chinese women.

OBJECTIVE

Chinese women have been shown to have a higher incidence of severe perineal laceration compared to other ethnic groups. We sought to test the hypothesis that this risk is related to body mass index (BMI) or to a relative fetal-maternal size disproportion as measured by the ratio of the newborn birthweight to maternal BMI (BW:BMI).

METHODS

A retrospective cohort study was performed using a pre-existing obstetric database. Third- and fourth-degree perineal lacerations served as the primary outcome of interest. Logistic regression was used to compare Chinese women to other ethnic groups and adjust for confounders.

RESULTS

Three thousand and eighty-five singleton vaginal deliveries were identified, with BMI data available for 2281. Chinese women had a greater risk for severe perineal laceration compared to Caucasian (OR: 3.22; 95% CI: 0.73-14.32) and Hispanic women (OR: 2.88; 95% CI: 1.92-4.30). Multivariate analysis found that newborn birth weight plays a role (OR: 1.0012; 95% CI: 1.0007-1.0016), but BMI alone did not explain the discrepancy (P=0.89). However, the BW:BMI ratio appears to be a stronger predictor of laceration rate than either variable alone (OR: 1.011; 95% CI: 1.003-1.020).

CONCLUSION

The higher risk of severe perineal laceration in Chinese women compared to other ethnicities can be attributed, in part, to a relative fetal-maternal size disproportion.