Effects on serum hormone levels of low-dose estrogen in place of placebo during the hormone-free interval of an oral contraceptive.
BACKGROUND
The study was conducted to evaluate the effects of low-dose estrogen compared to placebo on ovarian activity during the traditional 7-day hormone-free interval (HFI) of an oral contraceptive (OC).


METHODS
Women were randomized to placebo or low-dose estrogen for 7 days during the HFI. Serum levels of estradiol, follicle-stimulating hormone (FSH), luteinizing hormone and inhibin B were obtained before, during and after treatment.


RESULTS
Mean hormone levels remained constant or only increased slightly for the low-dose estrogen group compared to greater more sustained increases observed for the placebo group. Estradiol, FSH and inhibin B levels were substantially higher for those on placebo. Differences were most noticeable by the end of the HFI and persisted into the subsequent cycle.


CONCLUSIONS
Subjects receiving low-dose estrogen for 7 days during the HFI demonstrated more pronounced ovarian suppression compared to placebo as evidenced by attenuation of increases in serum inhibin B, FSH and estradiol levels.
Reape
Kathleen Z
KZ
Duramed Research, Inc. Bala Cynwyd, PA 19004, USA. kreape@barrlabs.com
DiLiberti
Charles E
CE
Hendy
Christopher H
CH
Volpe
Edward J
EJ
D000293:Adolescent; D000328:Adult; D003278:Contraceptives, Oral, Hormonal / Q000008:administration & dosage*; D003279:Contraceptives, Oral, Sequential / Q000494:pharmacology*; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007265:Inhibins / Q000097:blood / Q000187:drug effects; D010053:Ovary / Q000187:drug effects*; D010919:Placebos / Q000008:administration & dosage; D011446:Prospective Studies
D003278:Contraceptives, Oral, Hormonal; D003279:Contraceptives, Oral, Sequential; D010919:Placebos; C422364:inhibin B; D004958:Estradiol; D007265:Inhibins; D005640:Follicle Stimulating Hormone