Changes in plasma vitamin A in lactating and non-lactating oral contraceptive users.
Plasma vitamin A and retinol-binding protein (RBP) concentrations have been studied in women using oral contraceptives (OC) for up to 4 years. In eight women taking an oestrogenic OC(1 mg of norethisterone acetate + 50 micrograms of ethinyloestradiol) values almost doubled within 6 months, but diminished somewhat after 4 years. Saturation of RBP with retinol remained fairly constant. Five lactating women who took progestogen-only OC (30 micrograms of levonorgestrel or 350 micrograms of norethisterone) showed no significant alteration in plasma vitamin A or RBP concentrations as compared with nine lactating non-OC users. All lactating women showed significant differences between the highest and lowest plasma vitamin A (P less than 0.005) and RBP (P less than 0.05) concentrations during the first 6 months of lactation. Highest values occurred 11-12 weeks postpartum and the lowest at 15-17 weeks. Percentage saturation of RBP with retinol was significantly higher (P less than 0.005) when vitamin A concentration was highest.
D000328:Adult; D003276:Contraceptives, Oral; D003277:Contraceptives, Oral, Combined; D005260:Female; D006801:Humans; D007774:Lactation; D008895:Milk, Human / Q000032:analysis; D011247:Pregnancy; D012177:Retinol-Binding Proteins / Q000032:analysis; D054839:Retinol-Binding Proteins, Plasma; D014801:Vitamin A / Q000032:analysis / Q000097:blood*
D003276:Contraceptives, Oral; D003277:Contraceptives, Oral, Combined; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; D014801:Vitamin A