P3.F102: An Epidemiological Update on Brachial Plexus Birth Injury in the United States

Background: DeFrancesco et al (JPO 2019) reported that the incidence of brachial plexus birth injury (BPBI) in the United States decreased from approximately 1.7 to 0.9 per 1000 live births between 1997 and 2012, a time over which the rate of Cesarean- (C-) section increased from 21% to 34%. The goal of this study was to use more recent data to update the epidemiological understanding of BPBI and describe changes in disease incidence, rates of C-section, and infant weight.

Methods: The KID database (1997-2019) was queried for hospital births, and cases of BPBI were identified by ICD-9 and ICD-10 coding. Clinical risk factors such as shoulder dystocia, heavy-for-dates, and macrosomia were extracted. Protective factors such as C-section birth and multiple gestation birth were also noted. Weighted proportion estimates were made using provided sampling information. These data were then compared over the study period to elucidate trends.

Results: The rate of C-section increased substantially from 1997 to 2006, coinciding with a decrease in BPBI incidence (Figure 1). The C-section rate then remained stable between 32.3% and 34.0% from 2006 to 2019, corresponding to a relatively stagnant rate of BPBI of approximately 1 per 1000 live births in 2019. Stratified analysis showed that C-section delivery was protective against BPBI across newborn weight classes, but the magnitude of this protective value was highest among newborns with macrosomia. Shoulder dystocia was the strongest risk factor for BPBI in a logistic regression model (odds ratio [OR] 56.9, p< 0.01). The OR for a newborn with macrosomia born via C-section (OR 0.581, 95% CI 0.365-0.925) was lower than that for a normal weight newborn born vaginally (OR 1.000, p=0.022). Medicaid insurance coverage (OR 1.176, 95% CI 1.124-1.230, p< 0.01) and female sex (OR 1.238, 95% CI 1.193-1.283, p< 0.01) were independent risk factors for BPBI (Table 1). Over time, the rate of BPBI was very strongly correlated to the rate of C-section (R2=0.980).

Conclusion: The incidence of BPBI has been steady at around 1 per 1000 live births since 2006, correlating with stable rates of C-section and fetal macrosomia in the United States. Time trends for C-section and BPBI rates demonstrate an inflection point between 2000 and 2003, which may reflect updated American Congress of Obstetricians and Gynecologists (ACOG) practice recommendations that were established around that time and stated that planned C-section should be considered for large neonates to prevent shoulder dystocia. Continued monitoring of national trends in BPBI incidence, and the factors that influence it, are essential to increase awareness and inform prevention efforts.