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A genome-wide association study (GWAS) of educational attainment was conducted in a discovery sample of 101,069 individuals and a replication sample of 25,490. Three independent single-nucleotide polymorphisms (SNPs) are genome-wide significant (rs9320913, rs11584700, rs4851266), and all three replicate. Estimated effects sizes are small (coefficient of(More)
Self-selection in epidemiological studies may introduce selection bias and influence the validity of study results. To evaluate potential bias due to self-selection in a large prospective pregnancy cohort in Norway, the authors studied differences in prevalence estimates and association measures between study participants and all women giving birth in(More)
BACKGROUND Total homocysteine (tHcy) measured in serum or plasma is a marker of folate status and a risk factor for cardiovascular disease. OBJECTIVE Our objective was to investigate associations between tHcy and complications and adverse outcomes of pregnancy. DESIGN Plasma tHcy values measured in 1992-1993 in 5883 women aged 40-42 y were compared with(More)
OBJECTIVE To describe birthweight by gestational age in Norway for the period 1967-1998, evaluate secular trends and provide new standards for small for gestational age for 16 to 44 weeks of gestation. SUBJECTS AND METHODS The analyses were based on more than 1.8 million singleton births, covering all births in Norway for a 32 year period. Percentiles for(More)
BACKGROUND Plasma total homocysteine (tHcy) has been associated with hip fracture but not directly with bone mineral density (BMD). We examined the association of hip BMD with levels of plasma tHcy, folate, and vitamin B12 and the methylenetetrahydrofolate reductase (MTHFR) 677C-->T and 1298A-->C polymorphisms. METHODS Bone mineral density was measured(More)
BACKGROUND The vast scientific literature on smoking and health contains few large studies with direct estimates of long-term mortality by smoking habits. Data have been lacking, particularly for women. OBJECTIVE To study smoking and deaths and causes of death in women and men of middle age (40 to 70 years of age). DESIGN Population-based cohort study.(More)
BACKGROUND There is evidence for an effect of cigarette smoking on risk of oral clefts. There are also hypothetical pathways for a biologic effect involving toxic chemicals in cigarette smoke. METHODS We performed a combined case-control and family-triad study of babies born with oral clefts in Norway in the period 1996 to 2001, with 88% participation(More)
OBJECTIVE To use familial patterns of recurrence of pre-eclampsia to investigate whether paternal genes expressed in the fetus contribute to the mother's risk of pre-eclampsia and whether mother's susceptibility to pre-eclampsia is related to maternal inheritance by mitochondrial DNA. DESIGN Linked data on pregnancies of different women who had children(More)
Familial correlations in birth weight and gestational age have been explained by fetal and maternal genetic factors, mainly in studies on offspring of twins. The aim of the present intergenerational study was to estimate and compare fetal and maternal genetic effects and shared sibling environmental effects on birth weight and gestational age and also on(More)