413: Prevalence of shoulder dystocia by maternal body composition and diabetes status


      We sought to examine the association between body mass index (BMI) and shoulder dystocia in women with pre-existing diabetes, with gestational diabetes, and without diabetes.

      Study Design

      This is a retrospective cohort study of women with singleton, non-anomalous, term pregnancies between 2007 and 2011 using linked vital statistics and ICD-9 data. Chi-square tests were used to compare rates of shoulder dystocia in diabetic and non-diabetic women categorized by BMI class. Pre-pregnancy BMI was categorized into underweight (<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), obesity I (30-34.9 kg/m2), obesity II (35.39.9 kg/m2), morbid obesity (40-49 kg/m2) and super obesity (>50 kg/m2). Multivariable logistic regression was used to estimate adjusted odds ratio (aOR) of shoulder dystocia by BMI class and by diabetes classification, controlling for maternal height, race/ethnicity, age, education, insurance status, and prenatal care.


      The cohort of 1,384,790 consisted of 232,925 (16.8%) obese pregnant women. Overall, we found that higher BMI class was associated with increased odds of shoulder dystocia, independent of diabetes status (Figure 1). Underweight pre-pregnancy BMI was associated with decreased odds of shoulder dystocia when compared to normal weight. When compared to women without diabetes, those with gestational and pre-existing diabetes had significantly increased odds of shoulder dystocia (aOR 1.50, 95% CI 1.43-1.57; aOR 3.04 95% CI 2.68-3.46, respectively) (Table 1). A significant association was demonstrated between BMI category and shoulder dystocia for those with gestational diabetes and no diabetes. In contrast, we did not find a statistically significant relationship between BMI class and shoulder dystocia among women with pre-existing diabetes.


      Diabetes status and higher BMI category are associated with increasing prevalence of shoulder dystocia. Prenatal education for women in these categories should emphasize the potential of shoulder dystocia as an adverse obstetrical outcome.
      Figure thumbnail fx1
      Figure thumbnail fx2