How fertile am I at age 40?

Fertilily at age 40. Unfortunately, at age 40 a woman is past the peak of fertility. The only way to assess her fertility to perform blood testing for certain hormones on cycle 2 or 3 of a menstrual cycle. Although not perfect is will give an assessment of her ability to conceive.
See doctor. Fertility decreases with advancing age, probably starting in the early 30's. While age is definitely a signficant factor, other variables may help to better specify one's individual prognosis for conceiving - one's pregnancy history, ovarian reserve testing, other reproductive factors (is uterus normal? Ovulatory status? Partner's semen analysis normal?). Thus, best to see one's doctor.