en Midwifery Original Article <br> <span style="font-size:14px;"><span style="font-family:Times New Roman;"><b>Background:</b> Food intake and metabolism might play central roles in causing and treating menstrual disorders. Vitamin D may lead to the improvement of folliculogenesis through anti-Mullerian hormone (AMH). This study aimed to compare the effect of vitamin D intake with that of the combined oral contraceptive (COC) capsules on ovulatory dysfunction.<br> <b>Methods:</b> This study was conducted on 60 eligible women referred to Kowsar Qazvin Hospital with a complaint of abnormal uterine bleeding (AUB). They had a history of excessive, long, and irregular bleeding. The participants in the control and intervention groups received 1 oral LD capsule and a combination of vitamin D and LD capsules on a daily basis for 3 months, respectively. The menstrual bleeding volume, the number of menstrual days, and the menstrual cycle length were evaluated before, during, and after the intervention. The Mann-Whitney U test, Friedman test, independent t test, and Cochran Q test were used in SPSS version 24 for data analysis. P values less than 0.05 were considered statistically significant.<br> <b>Results:</b> The menstrual bleeding intensity decreased significantly in the intervention group (vitamin D&ndash;LD capsule; P = 0.001). Over time, both intervention and control groups showed a significant improvement in the number of menstrual days and menstrual cycle length, resulting in a more normal menstrual cycle. However, these 2 parameters remained more natural in the intervention group, a finding which did not indicate any significant differences.<br> <b>Conclusion</b>: Vitamin D can be used along with LD capsules as a supplementary treatment to lessen menstrual bleeding intensity.</span></span> combined oral contraceptive, abnormal uterine bleeding (AUB), menstrual bleeding, vitamin D 66 72 http://nmj.goums.ac.ir/browse.php?a_code=A-10-1502-1&slc_lang=en&sid=1 mahdis chegini mahdis.g.chegini@gmail.com 100319475328460012230 100319475328460012230 No Department of Midwifery, Faculty of Nursing and Midwifery, Qazvin University of Medical sciences, Qazvin, Iran khadije hajizade hajizade_k@yahoo.com 100319475328460012231 100319475328460012231 No Department of Midwifery, Tabriz University of Medical Sciences, Tabriz, Iran azize farshbaf farshbafa@tbzmed.ac.ir 100319475328460012232 100319475328460012232 No Physical Medicine and Rehabilitation Research Centre, Aging Research Institute, Tabriz University of Medical Sciences, Tabriz, Iran fateme lalooha lalooha44@yahoo.com 100319475328460012233 100319475328460012233 No Obstetrics and Gynecology Department, School of Medicine, Kosar Teaching Hospital, Qazvin University of Medical Sciences, Qazvin, Iran Mahnaz Shahnazi shahnazimahnaz@gmail.com 100319475328460012234 100319475328460012234 Yes Department of Midwifery, Faculty of Nursing and Midwifery, Tabriz University of Medical Sciences, Tabriz, Iran