More and more women are having their first child after the age of 35. This age also coincides with the natural decline in fertility potential. The decline in fertility potential, or "ovarian reserve," is the natural consequence of the aging process on human eggs and aging eggs can impact pregnancy chances.

The human ovary has two major functions: The reproductive function or production of eggs (oocytes) and the steroidogenic function or production of hormones, mostly estrogens. The reproductive function of the ovary has a much shorter lifespan than the hormonal function, so fertility potential declines in the late 30s to early 40s, even though menopause occurs in the late 40s to early 50s. Each woman is born with a set number of eggs. This number is determined before birth and the pool of eggs is never replenished. A female fetus will have the greatest number of eggs around 16-20 weeks of pregnancy (6-7 million); at birth this number decreases to about 2 million, and by puberty to about 300,000. This constant and dynamic process of decline continues until menopause, and is not interrupted by birth control pills, pregnancy, or ovulation. From this reservoir of eggs, fewer than 500 eggs will ovulate during a woman's reproductive years.

Lower pregnancy rates and higher miscarriage rates are both the consequences of the aging process, and reflective of a decline in egg quality. Women ovulate their healthiest eggs during their 20s and early 30s. By the mid-30s the remaining eggs are of lower quality, and by the early 40s only eggs with very low fertility potential are available for ovulation or ovulation induction. This phenomenon is a normal biological process, which neither fertility medications nor lifestyle changes can halt. A healthy egg has two functions necessary for a successful pregnancy. First, it must have normal chromosomes, and second, it must be able to correctly combine its chromosomes with those of the sperm to produce a normally growing embryo.

Besides using age to determine pregnancy chances, we can use fertility tests such as antral follicle count (AFC) and a blood test for anti-Müllerian hormone (AMH). These tests help determine how many eggs remain (the ovarian reserve) in the ovaries' small sacs (follicles).

Various strategies for improving egg quality have been suggested, and some have been tested, but unfortunately these strategies have not shown improvements in pregnancy rates. An option for some women is to preserve their fertility with egg freezing. However, egg freezing does not help our patients who are currently in their mid-30s to 40s, and facing the challenge of infertility.

If fertility treatment is unsuccessful based on a diagnosis of diminished ovarian reserve, options include egg donation, adoption, or choosing to live childfree. While these decisions may be difficult, it is of some comfort to know that there are options available, as well as support to assist you in achieving your goal of building a family.