Ethnic background as a risk factor for permanent brachial plexus birth injury: A population-based study

Introduction: Brachial plexus birth injury is the most common birth injury causing permanent disability in Finland. This study aimed to assess risk factors of a permanent brachial plexus birth injury and calculate the incidence. Material and methods: This is a retrospective population-based study including all deliveries between 2006 and 2022 in Southern Finland. The number of children born, obstetric data, and migrant status were gathered from the registries of the Finnish Institute for Health and Welfare, and Statistics Finland. Race of the mothers of children with a permanent brachial plexus birth injury was recorded. The severity of permanent brachial plexus birth injury was assessed using the 3-month Toronto test score. A lower score was indicative of a more severe injury (scored 0-10). Results: One hundred of the 298 428 children born during the 17-year study period sustained a permanent brachial plexus birth injury (0.34 per 1000). Mothers of children with a permanent brachial plexus birth injury had a higher body mass index (29 vs. 24 kg/m(2)) and their pregnancies were more often complicated by diabetes (28% vs. 12%), shoulder dystocia (58% vs. 0.3%), and/or assisted deliveries (45% vs. 10%) compared with all other mothers (p < 0.001). Thirty two of the 52 725 children born to migrant mothers had a permanent brachial plexus birth injury (0.61 per 1000). The incidence of permanent brachial plexus birth injury was 5.7 times higher among children of Black migrants from Africa (18/11 738, 1.53 per 1000) compared with children of native mothers (0.27 per 1000). Black mothers had a higher body mass index at the start of pregnancy (29 vs. 26 kg/m(2), p = 0.02) compared with Caucasians. Children of Black mothers had a more severe injury compared with all others (p = 0.007) with a mean 3-month Toronto test score of 4.2 (range 0.0-6.5, SD +/- 1.6) vs. 5.6 (range 0.0-9.3, SD +/- 2.2). Conclusions: Shoulder dystocia and assisted delivery are the most important risk factors for a permanent brachial plexus birth injury. Black race was associated with a higher rate and a more severe permanent brachial plexus birth injury.