(735) The association between TOLAC in obese women and adverse maternal outcomes

The American College of Obstetricians and Gynecologists encourages trial of labor after cesarean (TOLAC) as a method of reducing the cesarean delivery rate. However, evidence regarding TOLAC outcomes in obese women is lacking. Several studies demonstrated an inverse relationship between obesity and TOLAC success but have not examined maternal morbidity in this population. We hypothesized that a TOLAC among obese women with a history of cesarean delivery is associated with decreased composite maternal adverse outcome (CMAO) as compared with planned repeat low transverse cesarean section (RLTCS).

Study Design:

In this population-based retrospective cohort study using the National Birth Certificate database from 2016-2020, we compared obese patients who attempted TOLAC at term (37+ weeks gestational age) to planned RLTCS. The primary outcome was a CMAO, defined as delivery complications including intensive care unit (ICU) admission, uterine rupture, unplanned hysterectomy, or maternal blood transfusion. A sensitivity analysis was performed of the CMAO excluding maternal blood transfusion. Relative risks were calculated and adjusted based on socio-demographic differences between the two groups.

Results:

794,278 patients met inclusion criteria; 126,809 underwent a TOLAC and 667,469 had a planned RLTCS. The overall composite maternal adverse outcome was significantly higher for patients undergoing TOLAC (9.0 per 1,000 live births) compared to RLTCS (5.3 per 1,000 live births; aRR 1.64, 95% CI 1.53-1.75) (Table 1).  Among individual conditions within the primary composite outcome, TOLAC was associated with increased ICU admission, maternal transfusion, uterine rupture, and unplanned hysterectomy (Table 1). In the sensitivity analysis, the rate of composite maternal adverse outcome excluding maternal transfusion was significantly higher in the TOLAC (5.1 per 1,000 live births) than the RLTCS cohort (1.9 per 1,000 live births; aRR 2.58, 95% CI 2.35-2.84).

Conclusion:

In obese patients with a history of cesarean delivery, TOLAC was associated with increased maternal adverse outcomes as compared to planned RLTCS.