Plasma lipids in women using progestogen-only oral contraceptives

Using a strict protocol, in an attempt to avoid confounding factors, healthy women were assigned at random to a continuous daily dose of either 30 micrograms levonorgestrel or 350 micrograms norethisterone. Volunteers were either aged 40-45 years, or were less than 30 years and 8-12 weeks post partum. Blood plasma lipids and lipoproteins were measured on specimens collected in the fasting state before treatment, then every month during progestogen treatment. After 6 months there was a small increase in plasma triglycerides, especially in older women, and also in a non-lactating younger group. Changes in lipoprotein-cholesterol fractions were insignificant, though there were significant pretreatment differences between the various groups.