New Delhi: According to a new study, use of contemporary birth control pills, patches or rings that contain both estrogen and progestin have been linked to a reduced risk for ovarian cancer in women of reproductive ages. The study backed up prior data that showed similar results with the use of older forms of oral birth control, widely used until the 1980s. The use of pills protected from nearly all types of ovarian cancer. The researchers followed the data of women aged between 15 to 79 from year 1995 to 2014. After eliminating women who had been treated for infertility, cancer, venous thrombosis or blood clots, the study was narrowed to women of reproductive age defined as ages 15 to 49. Nearly two million women were part of the study. The study then separated the women into three groups, those who had never used hormonal contraception, women currently using it or had used within the last year, and those who had stopped. It found that the risk of ovarian cancer was highest in women who had never used hormonal contraceptives and lower among women who had used the method at some point. The risk reduction appeared to strengthen with longer use of the combined hormonal birth control and diminished once use was stopped. Based on their data, researchers believe hormonal birth control prevented an estimated 21 per cent of ovarian cancers in the women included in the study. The findings are published in the medical journal BMJ.