This is reflected in the decreased ability to become pregnant and the increased rate of miscarriage with age. While we know that infertility increases with age, the precise age when a woman can no longer conceive varies among individuals. However, it is well documented that 30% of couples in which the female partner is age 35 or older will have problems with fertility.
Women are born with their entire supply of eggs. The rest of her life is spent losing the eggs she was born with. A typical woman will have about 3 to 4 million eggs at birth, declining to roughly 500,000 to 700,000 at the start of puberty. Each menstrual cycle will then release a batch of eggs until they are all gone – a time called menopause. This loss occurs monthly regardless of whether a woman is pregnant or is taking hormonal contraceptives such as birth control pills. As a result, experts have shown that female fertility begins to decline many years prior to the onset of menopause despite continued regular ovulatory cycles. As a woman ages, not only does a woman have less eggs, the eggs also have a higher chance of being chromosomally abnormal. Many scientists have shown that by age 40, at least 50% of the remaining eggs in a woman’s ovaries are chromosomally abnormal. Most chromosomally abnormal eggs will never fertilize or implant. When a pregnancy does occur with a chromosomally abnormal egg, the baby could have Down’s syndrome or another chromosomal disorder, and usually results in miscarriage.
Fertility is usually measured by the percentage chance a woman has to get pregnant each month. In women less than 35 years old there is a 20% chance of getting pregnant each month. By the age of 40, this percentage has dropped to only 5%. This is critical information for couples who eventually want to have children, but have delayed childbearing for their careers, economic reasons and the misconception that fertility doesn’t diminish with age. Delaying pregnancy may eventually reduce the chance that the couple will ever successfully conceive and deliver a healthy baby.
Testing For Age Related Infertility
There are several tests that help to predict fertility potential (ovarian reserve) and determine age related infertility in women:
- FSH (Follicle Stimulating Hormone) Blood Test: If you have a high level of FSH (>10 mIU/mL) in your blood at the beginning of your cycle (days 2-4), this may mean that your infertility is age related or you are experiencing premature ovarian dysfunction. In general, women with elevations of FSH have reduced chances of live birth with either ovulation induction or IVF compared to other women of the same age. Many studies have shown that even a single elevated early FSH may indicate a poor prognosis, even when values in subsequent cycles are normal.
- Estradiol Blood Test: If you have a high level of estradiol (>80 pg/mL) in your blood at the beginning of your cycle (days 2-4), this may mean that you are experiencing accelerated follicular development and may be associated with reproductive aging.
- Clomid (Clomiphene Citrate) Challenge Test: The Clomid Challenge Test (CCCT) is a sensitive means to measure ovarian reserve. The test involves an FSH and Estrogen blood test at the beginning of your cycle (days 2-4), followed by taking clomid 100 mg on Days 5-9, with another FSH and Estrogen blood test on Day 10. A high FSH level at the end of the CCCT may indicate age related infertility, and also predicts poor response to the fertility medications used during treatment. In general, an abnormal CCCT predicts that a successful pregnancy will be achieved only about 5% of the time.
- Anti-Mullerian Hormone (AMH): A blood hormone level which may be drawn at any time of month. While still considered investigational, fertility centers around the world are using this test as a marker of declining number of remaining eggs in a woman’s ovaries, and abnormalities may be a reason for concern and a heightened level of aggressiveness with fertility treatment, even prior to seeing elevations in FSH levels.
- Antral Follicle Count: This is the visual measurement performed by transvaginal ultrasound early in the menstrual cycle (days 2-4) which determines how many immature eggs are available per month and reflects the underlying egg supply and future response to ovarian stimulation. This number declines with age. This is also a reflection of the number of eggs that you and your fertility specialist have to work with on any given monthly cycle.
Age is a significant factor in determining how aggressive and how quickly AFC Physicians will start treatment. If you are near or over the age of 40, it is important to schedule your initial consultation as soon as possible to learn about the options that are available to you.