Evolution of plasma levels of apolipoprotein B,cholesterol and triglycerides in women during long-term oral contraception

Apolipoprotein B (apo B) was measured by a sensitive and specific double antibody radioimmunoassay in plasma from 15 normal women and 47 women taking oral contraceptives. The plasma apo B concentration in normal women was 0.90 ± 0.10 g/l (mean ±S.D.) whereas the overall value for all women taking contraceptives was 0.69 ± 0.19 g/l. The maximum decrease (p < 0.001) occurred in women investigated within three months after the beginning of the steroid intake, whose mean apo B value was 0.60 ± 0.12 g/l (n = 12); decreases found after 3–24 months of contraception were of lesser magnitude. Apo B decreases were associated with significant decreases (p < 0.01) in total plasma cholesterol, although the latter regained normal values after one year of contraception. Apo B and cholesterol values were in the normal range in women investigated after two years of steroid intake. An inverse trend was observed for plasma triglycerides, which showed a mean increase of 29% (p < 0.01) after three months of steroid intake, and then stayed elevated without significant change with time.