['To investigate whether hypertriglyceridemic dyslipidemia is a risk factor for either early or late onset pre-eclampsia.', 'Prospective cohort study and nested case-control study.', 'Aker Hospital: a university hospital with all levels of obstetric care.', '2,157 Caucasian pregnant women.', 'Blood samples were obtained from non-fasting subjects at 18 weeks of gestation. All samples were analysed for triglycerides, total-cholesterol, high density lipoproteins cholesterol and non-high density lipoproteins cholesterol. ApoB-100 were analysed in pre-eclamptic women and in 3:1 matched controls. The cohort data were analysed by multiple logistic regression and the case-control data by conditional logistic regression.', 'Adjusted odds ratios of early and late onset pre-eclampsia according to early second trimester serum concentration levels of lipids and ApoB-100.', 'Eighteen women developed early onset pre-eclampsia and 53 women developed late onset pre-eclampsia. In the cohort model, women with triglycerides above 2.4mmol/L had increased risk (OR 5. 1; 95% CI 1.1-23.1) of early onset pre-eclampsia compared with those with triglycerides levels < or = 1.5mmol/L. For women with high triglycerides: non-high density lipoproteins cholesterol ratios (>90 centile) the OR (95% CI) for early onset pre-eclampsia was 7.1 (2.3-22.0) compared with those with low ratios (< or = 50 centile). Similar associations were found in the case control model. We found no associations between plasma lipids and risk of late onset pre-eclampsia.'] Is dyslipidemia in early second trimester mainly a feature of women with early onset pre-eclampsia?