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.

ObjectiveThe International Association of Diabetes and Pregnancy Study Groups (IADPSG) recently proposed new criteria for diagnosing gestational diabetes mellitus (GDM). We compared prevalence rates, risk factors, and the effect of ethnicity using the World Health Organization (WHO) and modified IADPSG criteria.MethodsThis was a population-based cohort study of 823 (74% of eligible) healthy pregnant women, of whom 59% were from ethnic minorities. Universal screening was performed at 28±2 weeks of gestation with the 75 g oral glucose tolerance test (OGTT). Venous plasma glucose (PG) was measured on site. GDM was diagnosed as per the definition of WHO criteria as fasting PG (FPG) ≥7.0 or 2-h PG ≥7.8 mmol/l; and as per the modified IADPSG criteria as FPG ≥5.1 or 2-h PG ≥8.5 mmol/l.ResultsOGTT was performed in 759 women. Crude GDM prevalence was 13.0% with WHO (Western Europeans 11%, ethnic minorities 15%, P=0.14) and 31.5% with modified IADPSG criteria (Western Europeans 24%, ethnic minorities 37%, P< 0.001). Using the WHO criteria, ethnic minority origin was an independent predictor (South Asians, odds ratio (OR) 2.24 (95% confidence interval (CI) 1.26–3.97); Middle Easterners, OR 2.13 (1.12–4.08)) after adjustments for age, parity, and prepregnant body mass index (BMI). This increased OR was unapparent after further adjustments for body height (proxy for early life socioeconomic status), education and family history of diabetes. Using the modified IADPSG criteria, prepregnant BMI (1.09 (1.05–1.13)) and ethnic minority origin (South Asians, 2.54 (1.56–4.13)) were independent predictors, while education, body height and family history had little impact.ConclusionGDM prevalence was overall 2.4-times higher with the modified IADPSG criteria compared with the WHO criteria. The new criteria identified many subjects with a relatively mild increase in FPG, strongly associated with South Asian origin and prepregnant overweight.

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