Association of body mass index on time to fetal expulsion for individuals undergoing medication abortion over 13 weeks gestational duration

Objectives

This study aimed to examine the association of body mass index (BMI, kg/m²) with time to fetal expulsion for individuals undergoing medication abortion over 13 weeks.

Study design

This is a retrospective cohort study of singleton pregnancies undergoing medication abortion >13 weeks at a single academic medical center between 2020 and 2024. Our primary outcome was time to fetal expulsion. We categorized BMI into three groups (>25, 25–29.9, and ≥30) and compared median time to fetal expulsion. We used multivariable logistic regression models to assess the association of BMI with time to delivery ≥24hours.

Results

Of the 428 charts reviewed, 382 patients met the inclusion criteria with an average gestational duration of 25.0 weeks. Of these, 162 (42.4%) had a BMI >30 kg/m²; 120 individuals fell into the BMI 25 to 29.9 group (31.4%), and the remaining 100 individuals made up the BMI <25 group (26.2%). The median time to expulsion differed significantly among BMI categories (12 hours for BMI <25 [IQR 8–18], 14 hours for BMI 25–29.9 [IQR 8–22], 20 hours for BMI ≥30 [IQR 12–28], p < 0.001). After adjusting for gestational duration, history of cesarean section, or prior vaginal deliveries, individuals with a BMI ≥30 had 6.62 times the odds (95% CI 3.27–13.44) of having a time to expulsion ≥24 hours compared to BMI <25.

Conclusions

Individuals with a BMI >30 had significantly longer second and third trimester time to fetal expulsion. Induction protocols and counseling may need to be adjusted based on body size.

Implications

Individuals with a BMI >30 undergoing a medication abortion >13 weeks have longer time to fetal expulsion than those with a BMI <25. More research is needed to optimize induction protocols and abortion care for high BMI individuals.