Ovarian Reserve Testing Shows Your Fertility Window
Perhaps the greatest threat to a woman’s fertility is advancing age. Many women are now choosing to delay marriage until they are much older, and consequently, many are attempting pregnancy in their middle to late 30s and early 40s. Unfortunately, the biological clock has not changed to coincide with the evolution of our societal values. Fertility for women remains greatest in the late teens and early 20s. This is contrary to the situation for men, as most men remain relatively fertile throughout their adult lives.
Women are born with a lifetime supply of eggs and this supply begins to decrease before a woman is even born. Each month a group of follicles (eggs are contained in follicles) begins to grow. One of these follicles will begin to grow faster than the others and will eventually ovulate and release an egg. The remaining follicles will shrink and eventually be reabsorbed. The younger the patient, the larger the number of follicles that begin to grow each month.
As women age, the number of follicles, and thus the number of eggs, decline and those that remain may demonstrate a decrease in quality. This is known as diminishing ovarian reserve. Unfortunately, many women have no symptoms and notice no change in their menstrual cycle during the early phases of diminishing ovarian reserve. Some women report a generalized shortening of their cycles, but most of the time cycle length is unchanged. In later phases, as a woman approaches menopause, a lengthening of the menstrual cycle may be noted.
There are several tests that can assess a woman’s ovarian reserve, including a vaginal ultrasound which measures ovarian size and the number of antral (resting) follicles present and blood work such as FSH levels on day 3 of a cycle, or AMH, antimullerian hormone, which can be tested on any day of the menstrual cycle. In general, ovarian size and antral follicle count decrease with age. The number of antral follicles correlates with the number of recruitable, and possibly fertilizable, eggs.
How does a blood test for FSH level early in the menstrual cycle (usually performed on day 2, 3, or 4) assess ovarian reserve? FSH is a hormone produced by a gland in the brain called the anterior pituitary gland. Its production is related to the amount of “activity” in the ovary. When the ovary is young and “active” (containing many follicles), the anterior pituitary gland needs to produce only a small amount of FSH to get the ovary to respond. When the ovary is older and not as “active”, the anterior pituitary gland must work harder to get the ovary to respond and it does so by increasing the amount of FSH produced. Thus, by measuring the amount of FSH, one can assess ovarian status or reserve. Typically, FSH levels above 10 mIU/ml indicate a decline in ovarian function.
Antimullerian hormone, or AMH, is another blood test that is frequently used to assess ovarian reserve.This hormone is secreted by the ovary and therefore the blood level generally correlates with ovarian response. Women with larger amounts of ovarian follicles, i.e. women with polycystic ovaries or robust ovaries, may have high amounts of AMH, while women with borderline or diminished ovarian reserve may have low levels.
The decline in fertility can be difficult to predict. Because age-related fertility is known to decrease quickly in the mid-30s, women over the age of 35 who have been attempting pregnancy for six months should see a fertility specialist/reproductive endocrinologist. Fertility specialists are acutely aware of age-related infertility issues and rapidly move women through available treatments. Studies show that the overall cost of infertility treatments is less when a specialist is consulted.
For many older women, the best chance to achieve pregnancy is by undergoing in vitro fertilization (IVF). This way, every step along the pathway to conception is maximized. Still, some women will respond poorly to fertility medications and will have a slim chance of pregnancy, even with IVF. In these women, use of an egg donor may be a good option.
An egg donor is usually a young woman (less than 30 years of age) who undergoes IVF stimulation, and her resulting eggs are combined with the husband’s sperm in a petri dish. The resulting embryo is then transferred into the wife’s uterus. We have one of the largest and most successful donor egg programs in Texas. The IVF success rates for our donor egg program are high, meaning fewer cycles of IVF will probably be required to achieve pregnancy. This, in effect, minimizes treatment costs. Please see our section on the donor egg program for more information.