Ovulatory dysfunction during continuous administration of low-dose levonorgestrel by subdermal implants
Faundes, A.; Brache, V.; Tejada, A.S.; Cochon, L.; Alvarez-Sanchez, F.
Fertility and Sterility 56(1): 27-31
1991
ISSN/ISBN: 0015-0282 PMID: 1906017 DOI: 10.1016/s0015-0282(16)54411-2Document Number: 556593
The study sought to examine the endocrinologic profile of regularly menstruating users of levonorgestrel subdermal implants. This observational, prospective, case-controlled, comparative study occurred at the Family Planning Clinic of PROFAMILIA in Santo Domingo, Dominican Republic. 31 subjects agreed to receive Norplant contraceptive implants between 13-77 months prior to this study and there were 12 nonhormonal contraceptors who also volunteered to participate. Follicle stimulating hormone, luteinizing hormone, estradiol (E2), and progesterone (P) were serially assayed for 1 menstrual cycle, and almost 1/2 of the cycles of norplant acceptors were anovulatory: the remainder (55%) had some form of dysfunction such as diminished gonadotropin surge, luteal phase insufficiency (low P levels and shortened luteal phase), and E2 profiles different from controls. Anovulation is clearly 1 of the main mechanisms of Norplant action, but even in presumptive ovulatory cycles, the dysfunctions described could have contributed to the high contraceptive effectiveness of Norplant.