Ovulatory dysfunction during continuous administration of low-dose levonorgestrel by subdermal implants.
OBJECTIVE
To study the endocrinologic profile of regularly menstruating users of levonorgestrel subdermal implants.


METHODS
Observational, prospective, case-controlled comparative study.


METHODS
The Family Planning Clinic of PROFAMILIA, in Santo Domingo, Dominican Republic.


METHODS
Thirty one regularly cycling Norplant users and 12 nonhormonal contraceptors who volunteered to participate.


METHODS
Norplant contraceptive implants were inserted in 31 subjects between 13 and 77 months before this study.


METHODS
Follicle-stimulating hormone, luteinizing hormone, estradiol (E2), and progesterone (P) were serially assayed for one menstrual cycle.


RESULTS
Almost half of the cycles among Norplant users were anovulatory; all the rest (55%) had some form of dysfunction: diminished gonadotropin surge, luteal phase insufficiency (low P levels and shortened luteal phase), and E2 profiles different from normal controls.


CONCLUSIONS
Anovulation is clearly one of the main mechanisms of action of Norplant, but even in presumptive ovulatory cycles, the dysfunctions described possibly contribute to the high contraceptive effectiveness of Norplant.
Faundes
A
A
PROFAMILIA, Santo Domingo, Dominican Republic.
Brache
V
V
Tejada
A S
AS
Cochon
L
L
Alvarez-Sanchez
F
F
D000328:Adult; D000858:Anovulation / Q000139:chemically induced; D016022:Case-Control Studies; D003277:Contraceptives, Oral, Combined / Q000008:administration & dosage / Q000494:pharmacology*; D004343:Drug Implants; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D016912:Levonorgestrel; D007986:Luteinizing Hormone / Q000097:blood; D009644:Norgestrel / Q000008:administration & dosage / Q000494:pharmacology*; D010060:Ovulation / Q000187:drug effects*; D011374:Progesterone / Q000097:blood; D011446:Prospective Studies
D003277:Contraceptives, Oral, Combined; D004343:Drug Implants; D009644:Norgestrel; D011374:Progesterone; D004958:Estradiol; D016912:Levonorgestrel; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone