Prevalence of infertility rises dramatically as age increases.
Women in their late 30′s have 90 % of the baseline fertility rate. Fertility declines to
62 % of the baseline rate among women 40-44 years of age, and to 14 % for women 45-49 years of age. There is moderate decline in fertility rates until age 35 to 39 and much steeper decline thereafter. Age-related declines in fertility may be due, in part, to less frequent ovulation or to problems such as endometriosis, in which tissue similar to that lining the uterus attaches to the ovaries or fallopian tubes and interferes with conception. Uterine receptivity also declines with age.
If conception has not taken place after six months of trying, a woman over age 35 should consult her health care provider. Many cases of infertility can be treated successfully.
While women over age 35 may have more difficulty conceiving, they also have a greater chance of bearing twins. The likelihood of naturally conceived (with out fertility treatment) twins peaks between ages 35 and 39. Although this data should not serve as a basis for changing women’s career decisions, it does provide the basis for counseling infertile couple ab out their chances of pregnancy.