The STORK Groruddalen research programme: A population-based cohort study of gestational diabetes, physical activity, and obesity in pregnancy in a multiethnic population. Rationale, methods, study population, and participation rates

Background: Gestational diabetes mellitus (GDM) and obesity may cause adverse pregnancy outcomes for mothers and offspring. We have set up a research programme to identify predictors for GDM and fetal growth in a multiethnic population in Oslo to improve the identification of high risk pregnancies and reduce adverse short and long-term outcomes for mothers and offspring. Aims: To present the rationale, methods, study population and participation rates. Methods: Population-based cohort study of pregnant women attending the Child Health Clinics (CHC) in Groruddalen, Oslo, and their offspring. Questionnaire data, blood pressure, anthropometric measurements, and fasting blood and urine samples are collected (gestational weeks 8-20 and 28, and 12 weeks postpartum) and an oral glucose tolerance test (28 weeks). Physical activity is measured, three ultrasound measurements are performed and paternal questionnaire data collected. Routine hospital data are available for all mothers and offspring. Umbilical venous blood and placentas are collected, sampled, and stored and neonatal anthropometric measurements performed. Ethnicity is self-reported country of birth. Results: 823 women were included, 59% of non-Western origin. The participation rate was 74% (64-83% in main ethnic groups), mean age 29.8 years (95% CI 29.5-30.1) and median parity 1 (inter-quartile range 1). The cohort is representative for women attending the CHC with respect to ethnicity and age. A slight selection towards lower parity (South Asians) and age (Africans) was found. Few were lost to follow-up. Conclusions: Unique information is collected from a representative group of multiethnic women to address important public health problems and mechanisms of disease. Participation rates are high in all ethnic groups.