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Clinical Obstetrics

Poster Session 3

(867) Impact of BMI and Mode of Delivery on Neonatal and Maternal Outcomes of Nulliparas

Wednesday, February 14, 2024
8:30 AM – 10:00 AM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective:

To compare neonatal and maternal outcomes based on the attempted mode of delivery stratified by body mass index (BMI kg/m2).

Study Design:

This was a repeated cross-sectional analysis of US vital statistics Live Birth/Infant Death linked data from 2011 to 2020. We limited analyses to nulliparas with singleton pregnancies and cephalic presentation who delivered at 20 weeks or greater. Our primary outcome was a composite neonatal outcome defined as any neonatal death, neonatal intensive care unit (ICU), surfactant use, ventilation use, or seizure. Our secondary outcome was severe maternal morbidity (SMM) defined as any maternal ICU, transfusion, uterine rupture, and hysterectomy. Outcomes were compared according to BMI category ( < 18.5, 18.5-24.9, 25-29.9, 30-39.9, 40-49.9, and 50-69.9) between individuals who attempted labor and individuals who opted for non-labor cesarean delivery. Adjusted relative risks (aRR) with 99% confidence intervals were calculated using modified Poisson regression.

Results:

Of 9,711,230 individuals, 462,201 had BMI < 18.5, 4,882,537 had BMI 18.5-24.9, 2,342,705 had BMI 25-29.9, 1,663,303 had BMI 30-39.9, 317,913 had BMI 40-49.9, and 42,571 had BMI 50-69.9. Table 1 shows the aRRs for each BMI class, with individuals who attempted labor being the referent group. Compared to attempting labor, non-labor cesarean was associated with an increased risk of the composite neonatal outcome in all BMI classes- BMI < 18.5, 18.5-24.5, 25-29.9, 30-39.9, 40-49.9, and 50-69.9 (range of aRRs 1.12-1.44). Compared to attempting labor, non-labor cesarean was associated with an increased risk of SMM in BMI < 18.5, 18.5-24.5, 25-29.9, and 30-39.9 (range of aRR 1.20-1.77). However, there was no significant difference in severe maternal morbidity in BMI 40-49.9, and 50-69.9.

Conclusion:

Attempting labor was associated with improved neonatal outcomes in all BMI classes as well as improved maternal outcomes except for BMI 40-49.9 and 50-69.9 compared to non-labor cesarean. Even for individuals with high BMI, it is reasonable to allow an attempt for vaginal delivery.