Incidence changes in risk factors associated with the decreasing number of birth-related clavicle fractures in Finland: A nationwide retrospective birth cohort from 2004 to 2017.

Background: A clavicle fracture is one of the most common birth injuries. The objective of this study was to examine whether the decreased incidence of birth-related clavicle fractures in Finland is because of temporal changes in their predisposing factors.

Methods: For this nationwide population-based study, we used the Finnish Medical Birth Register and the Care Register for Health Care databases. The study population included all singleton, live-born newborn born spontaneously or by vacuum-assisted delivery, in cephalic presentation ≥37 weeks of gestation. The incidences of clavicle fractures, pregnancy characteristics, and risk assessments for fracture were calculated and compared between two time periods: 2004-2010 and 2011-2017.

Results: A total of 629 457 newborn were born vaginally between 2004 and 2017. The clavicle fracture incidence decreased from 17.6/1000 to 6.2/1000 live births. Shoulder dystocia, diabetes, and birthweight ≥4000 g were the strongest predisposing factors. The incidence of birthweight ≥4000 g decreased, meanwhile type 1 diabetes and shoulder dystocia remained stable and gestational diabetes, type 2 diabetes, and maternal obesity increased in the later study period. The incidence of clavicle fractures without known predisposing factors declined. Simultaneously, the cesarean birth rate remained stable (13.2%-13.1%), although the rate of vacuum-assisted deliveries increased (8.5%-9.5%).

Discussion: The incidence of clavicle fractures decreased, even though the incidence of most risk factors remained stable or increased, and the cesarean birth rate remained stable. This decline may be related to the reduction of fracture incidence among deliveries without known risk factors, and the decrease in birthweight ≥4000 g.