Evidence for the benefit of prenatal pelvimetry in breech presentation at term: A low intertuberous distance is associated with assisted head delivery and short‐term neonatal morbidity

OBJECTIVE: Guidelines on vaginal breech delivery have several restrictions concerning feto-maternal parameters. To date, they neglect the impact of prenatal pelvimetry, especially of the intertuberous distance (ITD), in nulliparous women attempting vaginal breech birth. METHODS: We performed a prospective cohort study involving 876 nulliparous women with a breech presentation at term, analyzing the impact of the ITD measured with magnetic resonance imaging (MRI) imaging prior to delivery on maternal and fetal short-term outcome parameters, as well as the necessity for manual assistance during vaginal breech delivery. Bivariate linear and nominal regression as well as multivariate adjusted nominal-logistic regression with Walds-testing was performed. RESULTS: We found a significant negative correlation between the ITD and fetal short-term morbidity (odds ratio [OR] per cm 0.56, 95% confidence interval [CI]: 0.31-0.98, P = 0.048). Significance was not reached when excluding deliveries with an ITD of below 11 cm. Multivariate adjusted regression showed a significant correlation of cesarean section and ITD (OR 0.72, 95% CI: 0.62-0.85, P < 0.001). In a multivariate subcohort analysis of all vaginal deliveries, the ITD was significantly associated with assisted head delivery (OR 0.67, 95% CI: 0.54-0.83, P < 0.001) and fetal short-term morbidity (OR 0.44, 95% CI: 0.20-0.90, P = 0.031) when adjusted to fetal birth weight, head circumference and the obstetrical conjugate (OC). When cases with an ITD of below 11.5 cm were excluded, no significant association of the ITD and fetal short-term morbidity was detected. CONCLUSION: Prenatal pelvimetry in breech presentation at term can be used to select patients for vaginal birth attempts. Women with an intertuberous distance (ITD) of below 11 cm might benefit from a cesarean section recommendation.