Effect of "missed" pills on oral contraceptive effectiveness.
OBJECTIVE
The purpose of this study was to determine whether missing pills in an oral contraceptive (OC) cycle resulted in folliculogenesis and eventual ovulation.


METHODS
Fifteen women selected from a population requesting tubal reanastomosis were randomized into three groups and issued pill packs missing four consecutive pills in specific sequences, as follows: group I, days 1-4; group II, days 3-6; and group III, days 6-9. Serum was drawn for assay of LH, FSH, estradiol (E2), and progesterone, and serial ovarian ultrasound examinations were done to study follicular development throughout the cycle at 4-day intervals.


RESULTS
No subject ovulated, as suggested by serum progesterone concentrations (not exceeding 0.63 ng/mL for any woman) and ultrasound assessment of follicular development (no follicular diameter exceeding 13 mm). The highest (mean +/- standard deviation) serum concentrations of LH and FSH in any group (13.25 +/- 18.71 and 14.40 +/- 7.71 mIU/mL, respectively) and of E2 (44.35 +/- 26.79 pg/mL) were observed during or immediately after the pill-free interval. Ovarian ultrasound examinations suggested suppressed folliculogenesis in all groups. No functional ovarian cysts were detected.


CONCLUSIONS
Oral contraceptives exerted a similar degree of pituitary and ovarian suppression even when the subjects missed four pills at varying times in a cycle. The anovulatory effect persisted when the OC pills were reinstituted and taken reliably after an interval of noncompliance.
Letterie
G S
GS
Department of Obstetrics and Gynecology, Tripler Army Medical Center, Honolulu, Hawaii.
Chow
G E
GE
D000328:Adult; D003279:Contraceptives, Oral, Sequential / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D006080:Ovarian Follicle / Q000502:physiology*; D010060:Ovulation / Q000502:physiology*; D010349:Patient Compliance; D011897:Random Allocation
D003279:Contraceptives, Oral, Sequential; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone