Maternal position and other variables: effects on perineal outcomes in 557 births

Damage to the perineum is common after vaginal delivery, and it can be caused by laceration, episiotomy, or both. This study investigated the effects of maternal position (lateral vs lithotomy) and other variables on the occurrence of perineal damage.

A retrospective study included the examination of hospital records from 557 women. The effects of demographic characteristics, gravidity, parity, duration of pregnancy, reason for admission, and mode of labor on perineal outcomes were investigated through univariate (independent sample t test, chi-square test) and multivariate analysis (logistic regression analysis).

Considering episiotomy as perineal damage, univariate analysis showed a protective effect of the lateral position (45.9% vs 27.9%, p > 0.001), and fewer episiotomies were performed (6.7% vs 38.2%) with this position. This protective effect for perineal damage disappeared on excluding women undergoing episiotomy from analysis. Multivariate analysis including all participants showed an increase of 47 percent in the likelihood of an intact perineum for the lateral position when compared with the lithotomy position (OR: 0.53; 95% CI: 0.36-0.78). Parity was associated with a reduction of 44 percent in perineal damage (OR: 0.56; 95% CI: 0.47-0.78, p < 0.001). Moreover, the lithotomy position was associated with significantly more episiotomies than the lateral position (7% vs 38%, p < 0.001). The odds of perineal damage increased in deliveries performed by physicians (OR: 2.92; 95% CI: 1.79-4.78).

Childbirth in the lateral position resulted in less perineal trauma when compared with childbirth in the lithotomy position, even after correcting for parity and birth attendant. The probability of an intact perineum increased in deliveries performed by midwives. (BIRTH 39:2 June 2012).