This slide exemplifies another effect that later childbearing in developed countries may have on overall fertility rates. As this figure shows, one of the strongest risk factors for infertility is age, and you can see that declines in fertility rates are observed as early as 30 to 35 years of age and are rather dramatic by age 40. Certainly, there is a continual, almost linear decline with age noted in this graph.

Increases in age-linked gynecologic maladies, such as endometriosis and fibroids, oocyte aging, and more time for exposure to STDs and to develop pelvic inflammatory disease (or PID) or multiple cases of PID likely explain this relationship.