1. Risk Factors for Recurrent Shoulder Dystocia, Washington State 1987-2004 Hillary Moore, MD University of Washington School of Public Health and Community Medicine Department of Epidemiology Maternal and Child Health Track Melissa Schiff, Thesis Advisor Susan Reed, Thesis Committee Member

2. June 7, 2006Recurrent Shoulder Dystocia Introduction Shoulder dystocia is an obstetric emergency in which an infant’s shoulders fail to deliver spontaneously after delivery of the head

3. June 7, 2006Recurrent Shoulder Dystocia Background Can result in significant infant morbidity and mortality as well as maternal morbidity Incidence of primary shoulder dystocia is 0.13- 1.16% of vaginal deliveries Four previous studies on recurrent shoulder dystocia –Very small number of cases –No adjustment for confounding –Referral center populations

4. June 7, 2006Recurrent Shoulder Dystocia Specific Aims What are the incidences of primary and recurrent shoulder dystocia? What are the risk factors for recurrent shoulder dystocia?

5. June 7, 2006Recurrent Shoulder Dystocia Methods Data Source: Washington State Longitudinal Birth Records Database linked with birth hospitalization discharge diagnoses, 1987- 2004

6. June 7, 2006Recurrent Shoulder Dystocia Methods Calculated primary and recurrent shoulder dystocia annual incidences Described maternal characteristics of women with and without recurrent shoulder dystocia and a subsequent cesarean section Used logistic regression to calculate Odds Ratios (OR) and 95% Confidence Intervals (CI) for the following risk factors: –Birth weight –Gestational age –Body Mass Index –Maternal weight gain –Gestational Diabetes –Operative assistance –Induction of labor

7. June 7, 2006Recurrent Shoulder Dystocia Methods Constructed a multivariable logistic regression model including maternal age and parity as confounding factors to obtain adjusted risk estimates for risk factors found to be significantly associated with recurrent shoulder dystocia Analysis was performed with stratification by diabetes status

8. June 7, 2006Recurrent Shoulder Dystocia Results

9. June 7, 2006Recurrent Shoulder Dystocia Results (continued) CasesControlsCesarean Section N=1,060N=4,238N=1,172 (%)(%)(%) Maternal Age (years) <202.03.71.6 20-2419.423.116.1 25-2933.131.130.0 30-3430.327.232.6 35+15.214.819.6 Parity 142.563.550.6 232.620.328.9 312.48.110.1 44.63.04.8 5+4.91.93.2

10. June 7, 2006Recurrent Shoulder Dystocia Results (continued) Risk FactorCrude ORAdjusted OR (95% CI) Gestational diabetes in subsequent pregnancy 1.5 (1.2, 2.0)1.2 (0.9, 1.5) Birth weight in index pregnancy (grams) <2500-- 2500-29990.4 (0.2, 0.7)0.4 (0.2, 0.7) 3000-3499ReferenceReference 3500-39992.0 (1.6, 2.4)1.9 (1.5, 2.4) 4000-44993.7 (3.0, 4.6)3.5 (2.8, 4.4) 4500-49993.8 (2.8, 5.2)3.3 (2.4, 4.5) 5000+6.5 (3.4, 12.6)4.5 (2.2, 9.3)

11. June 7, 2006Recurrent Shoulder Dystocia Results (continued) Risk FactorCrude ORAdjusted OR (95% CI) Operative delivery in index pregnancy Forceps 0.9 (0.7, 1.2)1.1 (0.8, 1.4) Vacuum 1.2 (1.0, 1.4)1.5 (1.3, 1.9) Both-- No operative assistanceReferenceReference Induction in subsequent pregnancy1.2 (1.0, 1.4)1.1 (0.9, 1.3)

12. June 7, 2006Recurrent Shoulder Dystocia Discussion Increasing magnitude of risk with increasing birth weight in the index pregnancy 50% increased risk of recurrence with vacuum assistance in the index pregnancy No significant association between gestational diabetes and recurrence after adjustment for maternal age and parity No effect modification by diabetes status Caesarean sections after primary shoulder dystocia Limitations

13. June 7, 2006Recurrent Shoulder Dystocia Conclusion Based on our population-based study, birth weight and vacuum assistance in the index delivery indicate increased risk of recurrence in a subsequent delivery In the context of an increasing primary shoulder dystocia incidence, identification of risk factors for recurrent shoulder dystocia is needed for clinical decision-making

14. June 7, 2006Recurrent Shoulder Dystocia Thank you Melissa Schiff Susan Reed Bill O’Brien Sara Donahue and my MCH colleagues Supported in part by Project #T76 MC 00011from the Maternal and Child Health Bureau (Title V, Social Security Act), Health Resources and Services Administration, U.S. Department of Health and Human Services.