Dear Doctor, How exactly does delaying to reproduce increase the risk of cancer in women? Aline Dear Aline, The prevalence of cancer is indeed increasing among women worldwide. Cancers like breast cancer are occurring at a younger age, growing more aggressively. The basic reason is lifestyle factors, including delay to reproduce. Women in their quest for higher studies, career making, are delaying to have a baby or avoiding it altogether. Studies have shown that ,early beginning of menstrual periods, late menopause, not having a child or late mother hood, not breast feeding a child are risk factors for breast, endometrial and uterine cancers. Those who conceive in teens or early twenties have lower prevalence of cancer as compared to women who conceive in 3rd or 4th decades of life. These are situations where high estrogen levels are present in the body. Estrogen is known to cause proliferation of cells and cause oxidative stress to them, increasing cell damage, which enhances risk of cancer formation. Similarly, estrogen-containing contraceptives, hormone replacement therapy after menopause can enhance the risk. Use of alcohol, tobacco smoking, stress, fatty diet, junk or ready-to-eat processed foods, are other risk factors contributing to increase in number of cancer cases.