Category: Labor
Poster Session IV
Maternal obesity is increasing in the United States and is associated with higher likelihood of cesarean delivery. Induction of labor (IOL) between 39 and 40 weeks may be associated with decreased risk for cesarean. The purpose of this study was to analyze trends in labor induction and likelihood of vaginal delivery stratified by maternal body mass index (BMI).
Study Design:
This cross-sectional study used 2015-2020 US natality data from the National Center for Health Statistics. Low-risk nulliparous patients at term with vertex singletons were identified and further stratified based on pre-pregnancy BMI including underweight (BMI < 18.5), normal and overweight (BMI >18.5- < 30), obese (BMI >30- < 40), and morbidly obese (BMI >40). Likelihood of vaginal delivery with IOL from 39w0d to 39w6d in each BMI category was compared to all deliveries from 40w0d to 42w6d, using unadjusted and adjusted logistic regression models. Trends in IOL from 39w0d to 39w6d as a proportion of all deliveries were assessed with Joinpoint regression to estimate the average annual percent change (AAPC) with 95% CIs.
Results:
Of 3,357,494 deliveries that met inclusion criteria, 660,972 (19.6%) underwent IOL from 39w0d to 39w6d. Of the sample, 3.7% was underweight, 73.9% was normal or overweight, 17.3% was obese, and 5.1% was morbidly obese. The proportion of deliveries with IOL between 2015 and 2020 significantly increased among all BMI categories, with morbid obesity having the largest AAPC (15.6%, 95% CI 11.5%, 19.9%) (Figure). Overall, 74.6% of deliveries with IOL occurred vaginally (n=493,497) compared to 73.7% (n=1,987,267) of deliveries from 40w0d to 42w6d. In stratified adjusted analyses, vaginal delivery was significantly more likely with IOL among underweight (aOR 1.20, 95% CI 1.15, 1.24), normal BMI/overweight (aOR 1.11, 95% CI 1.10,1.12), obese patients (aOR 1.09, 95% CI 1.08, 1.11), but not morbidly obese patients (aOR 0.97, 95% CI 0.95, 0.99) (Table).
Conclusion: When compared to delivery at 40w0d to 42w6d, IOL at 39w0d to 39w6d was associated with a lower odds of cesarean delivery except for morbidly obese women.
Sbaa Syeda, MD
Fellow
Columbia University Irving Medical Center
New York, New York, United States
Brittany Arditi, MD, MSCR
Resident Physician
Department of Obstetrics and Gynecology, Columbia University Irving Medical Center
New York, New York, United States
Natalia S. Parra, MD (she/her/hers)
Resident
Columbia University Medical Center
Columbia, New York, United States
Nicole Krenitsky, MBA, MD
Resident
Columbia University Irving Medical Center/NewYork-Presbyterian
New York, New York, United States
Mary E. D'Alton, MD
Obstetrician and Gynecologist-in-Chief
Willard C. Rappleye Professor and Chair
Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Columbia University Irving Medical Center
New York, New York, United States
Maria Andrikopoulou, MD, PhD
Columbia University Irving Medical Center
New York, New York, United States
Alexander M. Friedman, MD
Columbia University Irving Medical Center
New York, New York, United States
Timothy Wen, MD,MPH (he/him/his)
Clinical Fellow
University of California, San Francisco
San Francisco, California, United States