Exercise, Weight and Infertility Couples with infertility often wonder if lifestyle habits might compromise their fertility. Two important lifestyle factors, weight and exercise, can affect fertility. Low weight or weight loss can lead to a decrease in an important hormonal "message" that the brain sends to the ovaries in women and testes in men. Stress and Infertility Although infertility is a highly stressful experience, there is very little evidence that infertility can be caused by stress. In rare cases, high levels of stress in women can change hormone levels and cause irregular ovulation. Infertility Aging and Infertility in Women Female fertility begins to decline many years prior to the onset of menopause despite regular ovulatory cycles. Although there is no strict definition of advanced reproductive age in women, infertility becomes more pronounced after the age of 35. A classic report on the effect of female age on fertility found that the percentage of women not using contraception who remained childless rose steadily according to their age at marriage. Prediction of Fertility Potential in Female Patients A woman's reproductive potential declines with age. This is reflected in the decreased ability to conceive (become pregnant) and an increase in the rate of spontaneous abortions (miscarriages). Although fecundity (the ability to achieve a pregnancy which results in a live birth) decreases in all women as they age, the precise age when a woman can no longer conceive varies between individuals.