Could vitamin d boost fertility? new study investigates

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

* INCLUSION CRITERIA: In order to be eligible to participate in this study, an individual must meet all of the following criteria: * Provision of signed and dated informed consent form * Stated willingness to comply with all study procedures and availability for the duration of the study * Having natural, spontaneous menstrual cycles (no hormonal therapy) less than 50 days in length. * Aged 19-40 years * Ability to take a vitamin D capsule and willing to adhere to the weekly regimen * If sexually active, use of a non-hormonal contraceptive method. EXCLUSION CRITERIA: An individual who meets any of the following criteria will be excluded from participation in this study: * No menstrual period in the last 50 days, or, a typical menstrual cycle length \<16 or \>49 days. * Use of a vitamin D supplement for more than one month and on more than 15 days out of each month. Volunteers will be asked to check their supplement label for vitamin D content. * Unwilling to abstain from taking non-study vitamin D supplements during the study or if already taking a medically-advised vitamin D supplement. * Use of a calcium supplement (including certain antacids) and unwilling to abstain from taking a calcium supplement during the study. * Known polycystic ovarian syndrome * Depo-provera use in the previous 12 months * Current use of any hormones, including birth control * Current use of a hormonal intrauterine device (IUD) * Current pregnancy or lactation, trying to become pregnant, or planning to try in the next four menstrual cycles or 5 months. * History of seizure disorders * Celiac disease * Crohn s Disease * Body mass index \>35 * Aged \<19 or \> 40 years * Presence of known contraindications for vitamin D supplementation, history of any of the following: calcium disorder or hypercalcemia, tuberculosis or granulomatous disease, metastatic bone disease, sarcoidosis, Williams syndrome, kidney disease (kidney stones, renal failure or dialysis, lupus nephritis) * Known liver disease (cirrhosis) * History of cancer other than skin cancer. * History of anorexia nervosa, bulimia or an eating disorder * Use within the past 60 days, of exogenous hormones * Type 1 or Type 2 diabetes * Known heart disease * Gastric bypass surgery * Unwilling or unable to complete study activities, e.g. collect daily urine specimens, have blood drawn, complete daily diaries, attend in person study visits 25\. Non-English speaking * Due to the complexity of daily/weekly diaries, testing and procedurerequirements, all consents, instructions and questionnaires are provided in English. Therefore, all participants must be able to able to read and speak English.