Vitamin D Supplementation Trial

About 1.5 million U.S. women of reproductive age are estimated to be infertile. Many more have difficulty getting pregnant. Menstrual cycles are an indicator of a woman s general health. Menstrual cycle changes may predict difficulties in getting pregnant. Researchers want to see what role vitamin D may play in menstrual cycle health.

Objective:

To examine the effect of vitamin D supplementation on the hormones that come from the brain and the ovary during a menstrual cycle.

Eligibility:

Women aged 19-40 who have spontaneous menstrual cycles (are not taking any hormones) less than 50 days in length.

Design:

Participants will fill out a screening survey about their demographics and health history. It will take 5-10 minutes to complete.

Participants will have 3 study visits. Participants who are deficient will be randomized to receive either a lower or higher dose of vitamin D supplements. Participants who are sufficient will receive placebo. If they are vitamin D deficient, they will not get the placebo. They will take the capsules by mouth, once per week, for 3 menstrual cycles (or about 90 days).

Participants will have physical exams. Their height, weight, body fat percentage, blood pressure, and waist-hip ratio will be measured. They will give blood samples. They will have vaginal and oral swabs.

Participants will keep a daily menstrual diary. They will do daily home ovulation testing. They will collect urine at home. Some women may collect menstrual blood at home.

Participants will fill out an online survey. It will ask about their health, diet, and physical activity; birth control use; pregnancy history; menstrual cycle; smoking and drinking habits; education; and occupation. It will take 20-30 minutes to complete.

Participation will last for four menstrual cycles (about 4 months).