Country of birth and county of residence and association with overweight and obesity-a population-based study of 219 555 pregnancies in Norway

Background The aim was to study the effect of country of birth, educational level and county of residence on overweight and obesity among pregnant women in Norway. Methods Observational study based on Medical Birth Registry Norway and Statistics Norway. The study population consisted of 219 555 deliveries in 2006-2014. Body mass index (BMI) was registered at the first antenatal care visit. Multivariate regression analysis was used to explore the study aims. Results Overweight (BMI 25-29.9) was recorded in 22.3% of the women, obesity (BMI >= 30) in 12.2%. Highest rates of overweight (30.8%) and obesity (13.5%) was recorded among women from the Middle East and North Africa or with no education (30.7% and 17.2%). The prevalence of overweight and obesity was 39.5% in sparsely populated counties and 26.4% for women living in Oslo. Adjusted for country of birth, education level, age, parity, smoking and marital status, the relative odds of overweight and obesity were 65% (95% CI 59-72%) higher in sparsely populated counties compared to Oslo. Conclusions The prevalence of overweight (BMI >= 25) was 34.5%. The factors associated with overweight were living in rural districts in Norway, lower education and being born in countries in the Middle East or Africa.