Background. Certain risk factors for development of ischemic heart disease are influenced by pregnancy related changes of female sex hormone levels. Methods. As a part of the cardiovascular risk factor studies in Finnmark county, Norway, 1974-75 and 1977-78, cross-sectional clinical and non-fasting laboratory data were obtained prior to conception (n=463), during pregnancy (n=335), and following delivery (n=451). Results. Compared with prepregnancy values, total cholesterol was on average 7% lower in the first trimester (p<0.001), and 30% higher at the end of gestation (p<0,001). High density lipoprotein cholesterol was 38% higher at mid-pregnancy (p<0.001), but only 14% higher in the last trimester (p<0.01). Serum triglycerides were 18% lower in the first (p<0.001) and 123% higher in the third trimester (p<0.001). Blood glucose was 5% lower than baseline in mid-pregnancy (p<0.001). Except for the second trimester, when only 27% of women smoked, more than 40% of the women examined were smokers. Postpartum values were similar to prepregnancy levels, except serum triglycerides which remained 35% higher (p<0.001) and blood glucose (p<0.05). Conclusions. The major serum lipid fractions, and blood glucose, were significantly different during pregnancy and postpartum, which may influence the risk of cardiovascular disease development in women.