Three quarters of uterine rupture is not linked with C/S or induction.
While women with uterine scarring, usually from a previous cesarean, and those given uterotonic agents to induce labor are known to be at higher risk for uterine rupture during pregnancy, a full 13% of ruptures involve unscarred uteri and almost three-quarters (72%) occur during spontaneous labor, according to a population-based cohort study from the Netherlands.
Researchers followed all 98 maternity units in the Netherlands from August 2004 to August 2006. They counted 210 cases of uterine rupture during the 2-year period. Of these, 87.1% or 183 occurred in women with a scarred uterus. They calculated incidences of 5.1 and 0.8 per 10,000 women with and without uterine scars, respectively. Overall absolute risk was 1 in 1,709.
In addition to a prior cesarean section and induction of labor, the researchers found other risk factors to include the use of epidural anesthesia, a pre- or post-term pregnancy, being overweight or of a non-Western ethnic background, and advanced maternal age.