A study on the effects of Norplant implantable contraceptive on lipid, lipoprotein, and apolipoprotein metabolism in Singaporean women.

The Norplant subdermal implants system is rapidly becoming acceptable as a contraceptive system all over the world. Earlier studies in Singapore indicated that the implants do not appear directly contributory to cardiovascular risk. However, extraneous environmental effects could have contributed to the observed changes. In this study, when nonsteroid copper intrauterine device (IUD) users were used as control, we have shown that the findings are in concordance with the results of the earlier studies. There was a decrease in serum triglycerides, total cholesterol, and HDL and LDL cholesterol over the period of study. However, despite these changes the HDL cholesterol/total cholesterol ratio remained stable and was above 0.200. As regards apolipoprotein, there was generally a significant full in apolipoprotein AI, AII, and B. As a result, the apolipoprotein AI/AII ratio showed a significant decrease in the first 3 months before increasing close to its preinsertion value at 2 years. Similarly, the apolipoprotein AI/B ratio also stabilized at the end of 2 years. This study thus confirms our earlier findings that Norplant implants do not appear directly contributory to cardiovascular risk.