Cerebral palsy among children of immigrants in Denmark and the role of socioeconomic status

Abstract

Introduction The proportion of births by immigrants has been increasing rapidly in Denmark during the last decades. Children of immigrants have higher risk of being born preterm and with low birth weight, which are strong determinants for cerebral palsy (CP), compared with children born to Danish women. Objective To investigate differences in risk of CP between children of Danish-born mothers and children of immigrants and to explore to what degree socioeconomic status mediates the potential association between maternal immigrant status and CP. Method We conducted a register-based study including 1,274,653 children born in Denmark between 1981 and 2007 of whom 2807 had CP (2.2 per 1000). Mothers’ country of origin derived from nationwide registers was used to determine the mothers’ immigrant status. Children with CP were identified by linkage with the Danish National Cerebral Palsy Registry that includes all pre- and perinatal acquired CP cases that have been validated by neuro-pediatricians at age one to six years. Odds ratios (OR) of CP according to maternal immigrant status were estimated by using multiple logistic regression. We studied whether a potential association was explained by maternal educational level or household income by performing mediation analysis applying a counterfactual approach. Results In this study, 141,540 (11.1%) were immigrants; 3.5% from Western and 7.6% Non-Western countries. Children of immigrants from Western and Non-Western countries had lower risk of unilateral spastic CP than children of Danish mothers; OR = 0.6 (95% VI: 0.4–0.9) and OR = 0.8 (95% CI: 0.6–1.0), respectively. Children of Non-Western immigrants had higher risk of bilateral spastic CP compared with children of Danish mothers; OR = 1.3 (95% CI: 1.1–1.5), and it was the Turkish (OR = 1.7 (95%CI: 1.2–2.4) and Pakistani (OR = 1.7 (95% CI: 1.0–2.9) immigrants that accounted for the increased risk. Results from mediation analysis indicated that the association between maternal immigrant status and bilateral spastic CP was not mediated by socioeconomic status. Due to insufficient statistical power, the mediation analysis was not applicable for unilateral spastic CP. Conclusion Our results show that the risk of CP in children born in Denmark between 1981 and 2007 differed according to maternal country of origin. The higher risk of bilateral spastic CP in children of Non-Western immigrants, in particular Turkish and Pakistani, does not seem to be explained by inequality in education or household income. Future research should investigate whether the increased risk is caused by consanguineous parenthood, lifestyle factors, or suboptimal prenatal and obstetric care for immigrants.