Age and Infertility
Age and infertility is an increasing problem due to general societal trends for women to delay childbearing. Testing in 2010 is unable to predict with absolute certainty which patients will be successful through fertility treatment. Our office does not refuse treatment based on testing. We can offer probabilities and percentages based on lab work and age, but future potential is unknown at this time.
Delayed Childbearing
Many women are waiting until their 30s and 40s to have children. In fact, about 20 percent of women in the United States now have their first child after age 35. Women have a set number of eggs when they are born, and as they age their eggs also become older and have an increased risk of chromosomal abnormalities. From the time of birth to puberty, all eggs are "suspended in time". When menstrual cycles begin, one egg is selected from this pool of eggs every month. This decline in fertility potential, or "ovarian reserve", is the natural consequence of the aging process on human eggs.
Once one egg is selected for a particular menstrual cycle, the LH surge occurs and triggers completion of the ovulation process. Now the egg can be fertilized. The length of time the egg waits for selection as a dominant egg corresponds to the chronological age of the woman.
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 20's and early 30's. By the mid 30's the remaining eggs are of lower quality, and by the early 40's only eggs with very low fertility potential are available for ovulation. 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 combine its chromosomes with those of the sperm in a correct and efficient manner to produce a normally dividing and growing embryo. While eggs are suspended in time they are susceptible to injury which may result in chromosomally abnormal embryos. These embryos usually do not continue to grow and no pregnancy is established. If an abnormal embryo does result in a pregnancy, it is more likely to lead to an early miscarriage.
Ovarian Reserve Decreasing with Age
In contrast to males, females at birth have their entire oocyte compliment of one million which declines to approximately 400,00 by puberty. Only when the hormonal milieu is appropriate will one or more follicles proceed to maturity and ultimately to ovulation while unselected follicles undergo atresia. Thus, hundreds to thousands of follicles become atretic each month of reproductive life. Therefore, the later in life an oocyte is recruited, the longer it has been frozen in a relatively unstable state which may allow for chromosomal or spindle damage, each known to result in failure to achieve pregnancy, increased incidence of spontaneous abortion or, more rarely, chromosomally abnormal children. It is also felt that the more sensitive or more "functional" oocytes are recruited at an earlier age leaving the most dysfunctional for the waning years of reproduction life. For lack of a better term, this period has been dubbed the period of "diminished ovarian reserve."
What are the Causes of Decreased Ovarian Reserve ?
Diminished ovarian reserve refers to a group of patients at any age that are cycling regularly but whose ovaries, and the eggs contained within, have a markedly decreased ability to produce pregnancies. Risk factors for this entity include age > 35, previous ovarian surgery, single ovary, unexplained infertility, and history of poor stimulation with injectable ovulation drugs (3 or fewer follicles developed and or peak estradiol of less than 1000 pg/ml). The patients exhibiting diminished ovarian reserve have identifiable clinical characteristics. The patient's cycle intervals become subtly but progressively shorter with 21 to 27 day cycle intervals common. This is due primarily to a shortened follicular phase (first 14 days of the cycle) and correlates with patient histories of positive ovulation predictor kits on cycle day 9 or 10 (cycle day one is the first day of menses).
Role of Hormonal testing
We take many other factors into consideration when determining one's chance of pregnancy, such as age, prior pregnancy history, and reason for requiring IVF treatment, and we find that many patients are still candidates for fertility treatment despite having a low AMH level or elevated FSH level. We believe that our role is to counsel the patient as to the probability of success based on our experience and that the ultimate decision is up to her.
Two tests that we use most frequently to evaluate the ovarian reserve are the FSH (Follicle Stimulating Hormone) and Estradiol. These blood tests are performed between days 3 and 5 of the menstrual cycle ( the first day of flow is cycle day 1). FSH is the hormone secreted by your pituitary gland to stimulate your ovaries to produce estrogen. When the ovaries become resistant, FSH levels rise in an increased attempt to stimulate the ovaries to function. An FSH value above 10 mIU/ml is considered elevated and an Estradiol value above 68 pg/ml is elevated. By measuring a baseline FSH on day 3 of the cycle, we sometimes get an indication that the women is closer to menopause and has relatively less "ovarian reserve". Another way of saying this is that if the day 3 FSH is elevated, egg quality is reduced.
More recently, another hormone, AMH has been used to help assess ones fertility potential. AMH levels are predictive of the number of eggs retrieved in IVF cycles, but are not predictive of one's chance of pregnancy and therefore this test as well as others, cannot be used to exclude women from IVF treatment based solely on FSH or AMH levels.
