Oral Contraceptive Hormone-free Interval Pituitary/ Ovarian Activity

LH, FHS, Estradiol and Progesterone Activity During the 7-Day Hormone-Free Interval of Various Combined Oral Contraceptive Regimens

The degree of suppression and subsequent activation of the hypothalamic-pituitary-ovarian axis during the hormone-free interval in combined oral contraceptive (COC) hormone users varies depending on the dose of ethinyl estradiol in the formulation. This variation in activation may be associated with different side effects during the hormone free interval. Progesterone (P) remained suppressed during all 6 COC regimens (<1.8 ng/mL), which indicates continuous contraceptive efficacy during the 7-day hormone free interval of all formulations studied.

Inclusion Criteria:

• Healthy, reproductive age women
• 18 to 35 years old,
• seeking contraception from the general gynecology clinics of the LAC and USC Medical Center w
• taking one of 6 possible monophasic COC formulations for at least 3 cycles prior to enrollment
• regular menstrual cycles prior to COCs

Exclusion Criteria:

• Irregular bleeding
• bilateral oophorectomy
• amenorrhea
• hormone-sensitive cancer
• concurrent medications known to interfere with steroid metabolism (i.e., barbiturates, phenytoin, carbamazepine, ethosuximide, primidone, rifampin, tetracycline)