One-year follow-up of lipoprotein metabolism after pregnancy.

Serum lipid and lipoprotein fractions one day after delivery, 3 months later in lactating and nonlactating mothers and 12 months later after initiation of menstruation were investigated in a group of 62 women, 29 of which formed a truly longitudinal group. Total serum cholesterol decreased significantly within 3 months after delivery and a further significant decrease occurred during the following 9 months. LDL- and HDL-cholesterols showed also a significant decrease within the postpartal year. Serum triglycerides decreased within 3 months after delivery but no more significantly later. Apolipoprotein AI and B also decreased within 3 months after delivery. In lactating mothers, HDL-cholesterol: cholesterol ratio, apolipoprotein AI and apolipoprotein AI:B ratio were higher than in nonlactating women. During the luteal phase, serum cholesterol and LDL-cholesterol were lower and the HDL-cholesterol: cholesterol ratio was higher than earlier during the menstrual cycle. Data prove that pregnancy related changes in lipid metabolism did not wane within 3 months after delivery. They also show that lactation affects lipid metabolism.