Aging egg supply

From birth, females have a fixed-though plentiful-supply of eggs (ovarian reserve). As a woman ages past her mid-30s, her eggs gradually degrade, making it less likely that she will naturally conceive, or that an assisted reproductive technology (ART) procedure will result in pregnancy and a healthy baby.

Among American women in their 20s to mid-30s, over 35% give birth per ART cycle using their own eggs. As women age, the live ART birth rate gradually drops:¹

• To about 20% per IVF cycle by age 39.
• To 2% or less per cycle in women over age 43. Many women over age 40 choose to use donor eggs, which greatly improves their chances of giving birth to a healthy child.

While there is no definitive test of ovarian reserve, a woman's follicle-stimulating hormone (FSH) level can be measured to evaluate how well her ovaries are working. A high FSH level is a sign that the body is trying to stimulate the ovaries to make more egg follicles, but the ovaries are not responding and conception is unlikely.

A woman's FSH level can be tested using a blood sample:

• Early in her menstrual period, around day 3.
• Before and after a clomiphene challenge test, early in her menstrual period.

Citations

1. Centers for Disease Control and Prevention (2004). 2002 Assisted Reproductive Technology Success Rates: National Summary and Fertility Clinic Reports. Available online: http://www.cdc.gov/reproductivehealth/ART02/index.htm.