Skip to main content
SMFM 2024 Pregnancy Meeting Main banner
Final Program


Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Presentation Icons
Additional registration fee required
Additional registration fee required
Faculty have requested this content not be shared on social media
Faculty have requested this content not be shared on social media
CME Credit Offered
CME Credit Offered
Poster Icons
Foundation Awardee
Foundation Awardee
No Social Media
No Social Media
Back
Q&A

Clinical Obstetrics

Poster Session 3

(812) Impact of an increase from class II to III BMI on pregnancy outcomes

Wednesday, February 14, 2024
8:30 AM – 10:00 AM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective: Current ACOG guidelines regarding management of patients with obesity are based on pre-gravid body mass index (BMI). It is unclear if and how management recommendations should change when BMI class increases during pregnancy.

Study Design: This is a retrospective cohort study from 2009–2022 of patients with singleton gestations and BMI >35kg/m2. We included those who maintained or increased (>3 BMI points) BMI class during pregnancy and excluded those that decreased BMI class. The primary outcome was a composite of growth abnormalities (FGR/LGA), cesarean delivery, oligohydramnios, polyhydramnios, and stillbirth. A superiority analysis was performed for the composite outcome between patients who increased BMI class IIàIII and class II using a repeated measures logistic regression model adjusting for a history of the primary outcome, race/ethnicity, marital status, insurance, nulliparity, chronic hypertension and pregestational diabetes. The adjusted odds ratio was reported with the respective 95% confidence interval and p-value. An equivalence test was performed for the composite outcome between patients who increased BMI class IIàIII and class III using two one-sided tests from a repeated measures model with an equivalence margin of 4%, and adjusting for same characteristics as in the superiority analysis.  The adjusted 90% confidence interval and the higher p-value of the two one-sided tests were reported. A p-value < 0.05 was considered significant.

Results: 9,117 pregnancies were included: 2,481 (class II), 4,154 (class III), 2,482 (class IIàIII). Patients who increased from BMI class IIàIII had more adverse outcomes than those who maintained class II BMI (aOR 1.60, CI 1.36-1.89) and were similar to those with class III BMI (adjusted 90% CI -0.013-0.022, adjusted equivalence p-value < 0.01).

Conclusion: For patients that increase BMI class from IIàIII, it is reasonable to manage their pregnancies (with regards to antenatal surveillance and delivery timing) according to ACOG and institutional guidelines for patients with pre-gravid BMI class III.