Due to lack of funds, the study has been terminated upon recruiting less than desired number of subjects

Contraceptive failure is the primary cause of unintended pregnancy in the United States. With obesity rates at epidemic proportions, any association between obesity and strategies that prevent undesired pregnancies constitutes a significant public health and economic concern. Evidence from recent epidemiological studies and our preliminary data (sub-therapeutic levels of steroid hormones due to drug clearance and half-life) suggest that obesity reduces oral contraceptive efficacy. Furthermore, preliminary analysis suggested that a sub-group of obese women, defined by their own birth weight, are at higher risk of contraceptive failure. Further studies are necessary to investigate whether birth weight, a surrogate marker of in utero growth restriction, is a useful diagnostic marker for the identification of women prone to contraceptive failure. Such an understanding is critical to finding a contraceptive strategy with better efficacy for these women.

The overall goal of this project is to test pharmacokinetics of oral contraceptive agents in obese women with low birth weight and compare to obese women with normal birth weight. The main hypothesis for this proposal is that an adverse in utero environment programs the expression and function of enzymes and transporters that underlie pharmacokinetics of oral contraceptives, and leads to contraceptive failure.

Reproductive-aged, ovulatory women of obese BMI >30 kg/m2 with normal birth weight (5.5-8 lbs; n=10) and low birth weight (<5.5 lbs; n=10), will be placed on oral contraceptives for 1 month. At several key time points, synthetic steroid pharmacokinetics, gonadotropins (luteinizing hormone, follicle-stimulating hormone) and ovarian hormone levels (estradiol, progesterone) will be monitored.

Inclusion Criteria:

• age 18 to 35.
• single progesterone level of 3 ng/mL or greater during the luteal phase (days 18 to 25) in the menstrual cycle prior to dosing with oral contraceptives.

Exclusion Criteria:

• absolute/relative contraindications to ethinyl estradiol and levonorgestrel.
• impaired liver function.
• history of deep venous thrombosis.
• hypertension (> 140/90).
• diabetes with vascular changes.
• migraines with aura or neurological changes.
• history of myocardial infarction, pulmonary embolus, stroke or breast cancer.
• anemia (hematocrit < 36%).
• actively seeking or involved in a weight loss program (must be weight stable)
• pregnancy, breastfeeding, or seeking pregnancy.
• diagnosis of Polycystic Ovarian Syndrome.
• recent (4 week) use of hormonal contraceptives (patch or ring included), intrauterine, or implantable hormonal contraception.
• DepoProvera use within six months.
• current use of drugs that interfere with metabolism of sex steroids.
• smokers.
• uncontrolled thyroid dysfunction.

Reproductive-aged, ovulatory women seeking to initiate contraception with combined oral contraceptives will be recruited from the female population of the Portland, OR area. Subjects must have access to their birth weight record. Enrollment will be confined to women who have not used a hormonal contraceptive method for 30 days or more prior to enrollment.