Attempted and Successful Vacuum-Assisted Vaginal Delivery by Prepregnancy Body Mass Index

UMMS Affiliation

Division of Research, Department of Obstetrics and Gynecology; Division of Epidemiology of Chronic Diseases and Vulnerable Populations, Department of Quantitative Health Sciences; School of Medicine

Publication Date


Document Type



Maternal and Child Health | Obstetrics and Gynecology | Translational Medical Research | Women's Health


OBJECTIVE: To examine rates of attempted and successful vacuum-assisted vaginal delivery by prepregnancy body mass index (BMI).

METHODS: We conducted a retrospective cohort study of 2,084 women with singleton gestations needing operative delivery assistance and vacuum-eligible (fully dilated, +2 station or greater, 34 weeks of gestation or greater) using 2006-2014 inpatient records. Prepregnancy BMI was categorized as underweight (less than 18.5), normal weight (18.5 to less than 25), overweight (25 to less than 30), or obese (30 or greater). Logistic regression models estimated odds ratios (ORs) and 95% confidence intervals (CIs) of attempted and successful vacuum-assisted vaginal delivery by prepregnancy BMI adjusted for age, race, marital status, parity, diabetes, labor induction-augmentation, episiotomy, gestational age, and neonatal birth weight.

RESULTS: Thirty-nine percent of women requiring delivery assistance and eligible for a vacuum were overweight or obese, 79% had vacuum attempts, and 95.3% of attempted vacuum-assisted vaginal deliveries were successful. Compared with women who were normal weight prepregnancy (82.8%), women who were overweight or obese were less likely to have vacuum attempted (75.8%, OR 0.71, 95% CI 0.53-0.96 and 71.2%, OR 0.53, 95% CI 0.39-0.74, respectively). Among women with attempted vacuum-assisted vaginal delivery, successful delivery did not differ by prepregnancy BMI (92.6%, OR 0.54, 95% CI 0.21-1.37 for underweight; 94.5%, OR 1.07, 95% CI 0.57-2.00 for overweight; 96.3%, OR 1.09, 95% CI 0.51-2.33 for obese compared with 95.6% among normal-weight women).

CONCLUSION: Among women in need of operative delivery assistance, prepregnancy obesity was associated with lower likelihood of attempted vacuum-assisted vaginal delivery but, if attempted, success rates were similar to rates among normal-weight women. With significant morbidity of second-stage cesarean delivery in obese women, research should examine whether vacuum-assisted vaginal delivery may be appropriate for additional obese patients.


UMCCTS funding

DOI of Published Version



Obstet Gynecol. 2017 Feb;129(2):311-320. doi: 10.1097/AOG.0000000000001847. Link to article on publisher's site

Journal/Book/Conference Title

Obstetrics and gynecology


Sebastian Ramos, Nili S. Amir and Annika L. Bannon are medical students at the University of Massachusetts Medical School. Sebastian Ramos participated in this study as part of the Senior Scholars research program.

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