IRCT2012100110980N1.

Trial name or title	Effect of vitamin D on menstrual pain in women of childbearing age in comparison with placebo; double‐blind randomised controlled clinical trial
Methods	RCT
Participants	Inclusion criteria: women aged 18 to 30 years; with normal menstrual cycles (cycles lasted 21 to 35, with menstrual lasting 3 to 7 days); at least 4 consecutive painful periods in the past 6 months with a diagnosis of primary dysmenorrhoea; Serum 25‐hydroxyvitamin D level ≤ 30 ng/dL Exclusion criteria: secondary menstrual pain diagnosed by ultrasound examination; Previous and current use of intrauterine contraceptive devices within the 6 months prior; previous and current use of drugs including calcium or vitamin D within the 6 months prior; recent use of oral contraception drugs during the past 2 months; smoker; BMI ≥ 30; history of kidney stones, granulomatous disease, hyperparathyroidism, and any malignant disease. Location: Iran
Interventions	Group 1: Cholecalciferol 50,000 IU oral tablets, once a week for 8 weeks Group 2: Placebo, oral tablet, once a week for 8 weeks.
Outcomes	Menstrual pain severity before treatment, 2 months after the treatment, 1 month after finishing intervention, using the visual pain scale.
Starting date	19/02/2013
Contact information	Akbar Fotouhi (tumspre.news@sina.tums.ac.ir)
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