A 2-year longitudinal study was undertaken to investigate the effects of the implantable contraceptive Norplant® on lipid and lipoprotein metabolism. A group of 177 Norplant implants acceptors was recruited in five centers (Bangkok, Jakarta, Mexico City, Singapore, and Stockholm) and monitored during one baseline menstrual cycle and 3, 5, 11, 16, and 22 months after implant insertion. They were compared with a group of 174 copper intrauterine (IUD) device users who had blood sampling performed at comparable time points. Lipid changes were greatest 3 months after implant insertion and a slow reversal of these trends towards baseline was observed during the next 19 months. The main changes observed at 3 months were a 10% drop in total cholesterol, and an 11% drop in high-density lipoprotein (HDL)-cholesterol and apolipoprotein AI levels, together with a 19% decline in serum triglycerides. Variations in low-density lipoprotein (LDL)-cholesterol and apolipoprotein B levels were not significantly different from those observed in the group of IUD users. There was consistency in these findings between centers in that the changes were in the same direction but of different magnitude in different centers. It is concluded that lipid changes induced by Norplant implants will probably not affect the risk of atherosclerotic disease in women who use this contraceptive method.
- Lipid metabolism
- Norplant® implants