Third and fourth degree perineal tears--the risk of recurrence in subsequent pregnancy

To assess the risk of recurrence of third- and fourth-degree perineal tears (34DPT) and to determine whether previous 34DPT is an independent risk factor for 34DPT in subsequent deliveries.

The study group included all women who had a vaginal delivery complicated by 34DPT (2000-2012, N = 356) and subsequently delivered again in the same medical center (N = 204). The rate of recurrence of 34DPT was compared with a control group of women who had a previous vaginal delivery not complicated by 34DPT (N = 58 581) and had a subsequent delivery in the same time period (N = 23 045).

Women in the past-34DPT group had a higher rate of CS (18.6% versus 10.1%, p < 0.001), fetal head in occiput-posterior position (POP; 2.5% versus 0.7%, p = 0.004) and mediolateral episiotomy (25.5% versus 19.4%, p = 0.03). Women in the past-34DPT group had a higher rate of 34DPT in the subsequent delivery (2.0% versus 0.3%, p < 0.001). The rate of recurrence of 34DPT was considerably higher among women with past fourth-degree tear versus women with past third-degree tear (22.2% versus 1.0%, p < 0.001). 34DPT in previous pregnancy is independently associated with increased risk of 34DPT in subsequent delivery (OR = 4.6, 95%-CI 1.3-15.3).

Women who experienced 34DPT in their previous pregnancy have an increased risk for recurrence of 34DPT in subsequent pregnancy, especially in cases of past fourth-degree tears.