Retrospective cohort study published in American Journal of Obstetrics and Gynecology Volume 232, Issue 6 analyzed 872 deliveries complicated by shoulder dystocia at a tertiary care center between 2012 and 2021 to investigate the relationship between maternal prepregnancy body mass index (BMI), management maneuvers, and neonatal morbidity. It compared outcomes and maneuvers required across three maternal BMI categories: <30 kg/m² (nonobese), 30-34.9 kg/m² (obese class I/II), and ≥35 kg/m² (obese class II/III).
The study found that although shoulder dystocia duration did not differ by BMI, deliveries to mothers with BMI ≥35 kg/m² required more maneuvers, especially additional internal rotational maneuvers such as Rubin’s maneuver, and had a higher risk of neonatal injury (including brachial plexus injury and fractures). Composite neonatal morbidity was not significantly different after adjusting for confounders.
These findings suggest that higher maternal BMI impacts clinical management of shoulder dystocia and is associated with increased neonatal injury risk, underscoring the importance of tailored obstetric strategies for pregnant individuals with obesity.
Key Points
Study Population
872 singleton deliveries with shoulder dystocia, categorized by maternal BMI:
BMI <30 kg/m²: 602 individuals (69%)
BMI 30-34.9 kg/m²: 160 individuals (18.3%)
BMI ≥35 kg/m²: 110 individuals (12.6%)
Shoulder Dystocia Management
Median duration ~40 seconds across all BMI groups, no significant difference.
McRoberts maneuver and suprapubic pressure were the most common initial maneuvers.
Women with BMI ≥35 kg/m² more likely to require 2 or more additional maneuvers beyond initial steps.
Rubin’s maneuver was significantly more frequent in BMI ≥35 kg/m² group (34.6% vs. 22.4%, adjusted OR 1.63).
Neonatal Outcomes
Composite neonatal morbidity (injuries, seizures, low Apgar, hypoxic ischemic encephalopathy, death) not significantly different by BMI after adjustment.
Neonatal injury (brachial plexus injury or fracture) was nearly twice as likely in BMI ≥35 kg/m² group (adjusted OR 1.97).
NICU admissions were also higher in the high BMI group (adjusted OR 2.09).
Clinical Implications
Increased maneuvers required with higher maternal BMI may reflect more complex delivery management.
Increased neonatal injury risk highlights need for anticipatory planning and possibly individualized delivery strategies in obese patients.
Current shoulder dystocia prevention guidelines do not incorporate maternal BMI as a risk factor but may need reevaluation.
Limitations
Single-center retrospective nature limits generalizability.
Missing data on duration for some deliveries.
Inability to determine exact timing or duration of individual maneuvers.
Lack of universal cord gas data limits neonatal acidemia analysis.
"Higher maternal BMI complicates shoulder dystocia management and increases neonatal injury risk, emphasizing need for tailored obstetric care."
