A prospective observational study on tears during vaginal delivery: occurrences and risk factors.

Abstract

To ascertain the occurrence and distribution of various types of I-IV degree tears, during childbirth, and analyze risk factors for perineal II degree tears. A total of 2883 consecutive vaginal deliveries, during 1995-97 at Sahlgrenska University Hospital in Göteborg Sweden, were included. All tears were classified according to an especially designed protocol, and risk factors for II degree tears were evaluated by use of univariate and logistic regression analysis. Only 6.6% of nulliparous parturients had no detectable tear as compared to 34.2% in parous women. Almost half of the women suffered from a II degree tear during birth, and a higher proportion of nulliparous (16.6%) than parous (9.4%) women had extensive perineal lacerations. In addition, nulliparous were more likely than parous parturients to be subjected to a perineotomy (18.1% versus 5.6%). Stepwise logistic regression analysis revealed that the following factors remained independently associated with II degree tear: slight perineal edema, high infant weight, excellent visualization of perineum, increasing age of the mother, excellent cooperation of the women, protracted second phase (> 60 min) and duration of second phase < 30 min. The majority of women (78%) undergoing childbirth had a tear and 47.1% suffered from perineal lacerations. Nulliparous women were more likely to have severe perineal lacerations or episiotomies. Similar risk factors were found for II degree tears as previously shown for III/IV degree tears.