RESUMO
BACKGROUND: Maternal obesity has been associated with an increased risk for an abnormal progression of labour; however, less is known about the length of the third stage of labour and its relation to maternal obesity. OBJECTIVE: To determine if the length of the third stage of labour is increased in extremely obese women and its possible correlation with an increased risk for postpartum hemorrhage. STUDY DESIGN: This was a retrospective cohort study of deliveries from January 2008 to December 2015 at our university hospital. Women with a BMI ≥40 and a vaginal delivery were compared with the next vaginal delivery of a woman with a BMI <30. There were 147 women with a BMI ≥40 compared with 157 with a BMI <30. Outcomes evaluated the length of the third stage of labour and the risk for postpartum hemorrhage and included antepartum, intrapartum, and perinatal complications. RESULTS: Subjects in the extreme obese group were more likely to be African American, older, diabetic (pregestational and gestational), hypertensive, pre-eclamptic, had a preterm delivery, and underwent an induction of labour. The overall length of the third stage of labour was significantly longer in the extreme obese group, 5 minutes (3, 8 [25th and 75th percentiles]) compared with 4 minutes (3,7) (P = 0.0374) in the non-obese group. Postpartum hemorrhage occurred more often in the extreme obese group (N = 16/147; 11%) compared with the non-obese group (N = 5/157; 3%) (P = 0.01). There were no differences between groups in respect to the following: gravidity, parity, length of the second stage of labour, birth weight, GA at delivery, Apgar score, cord blood gases, hematocrit change, need for postpartum transfusion, operative delivery, and development of chorioamnionitis. After an adjustment for ethnicity, maternal age, diabetes, preeclampsia, preterm labour, hypertension, and induction/augmentation, the analysis failed to show a significant difference in estimated blood loss and postpartum hemorrhage between the groups. CONCLUSIONS: The length of the third stage of labour is longer in the extreme obese parturient. Postpartum hemorrhage also occurs more often, but after adjustments for confounding variables, it is no longer significant.