The Role of Hormones in Infertility
Fertility hormones at a glance
- Follicle-stimulating hormone (FSH) helps control a woman’s menstrual cycle and egg production, and can be tested to estimate a woman’s fertility potential.
- Estradiol, an important form of estrogen, can be measured to determine the quality of a woman’s eggs – an important factor in fertility.
- Luteinizing Hormone (LH) stimulates the release of eggs from the ovaries and prepares the uterus to receive a fertilized egg; LH levels can be measured to determine when ovulation will occur.
- Progesterone is produced just after ovulation to finish preparing the uterus for the arrival of a fertilized egg.
Follicle-stimulating hormone (FSH)
Follicle-stimulating hormone (FSH) helps control a woman’s menstrual cycle and egg production. During infertility testing, FSH is tested to determine a woman’s ovarian function and evaluate the quality of her eggs. The test is done on day 2 to 5 of the menstrual cycle. As a woman’s ovary function declines, the brain and pituitary gland increase the amount of FSH to stimulate the ovary to work “harder.” Thus the FSH test is a very indirect indicator of the ovarian status. However, in a few years this test may be replaced by the AMH test and antral follicle count.
Determining the blood concentrations of FSH on day 3 of the menstrual cycle may estimate fertility potential. In general, women with elevated levels of FSH on cycle day 3 have reduced chances of live birth with both ovulation induction and in vitro fertilization (IVF) compared to other women of the same age.
Estradiol (see below) must be measured as well, as elevations of estradiol can be an early warning of low ovarian reserve. High estradiol will suppress the FSH, giving false reassurance of normal values.
The laboratory method of measuring these hormone levels may vary considerably, so it can be difficult to compare blood levels that are measured at different laboratories or by different techniques. In addition, it is important that normal and abnormal test values be based on the pregnancy rates achieved by women studied at a particular center using the same laboratory methods.
Estradiol, an important form of estrogen, is tested in conjunction with follicle-stimulating hormone (FSH) to measure a woman’s ovarian function and to evaluate the quality of the eggs. Like FSH, it is done during days 3 to 5 of a woman’s menstrual cycle.The results of these tests are not absolute indicators of infertility but abnormal levels correlate with decreased response to ovulation induction medications and lowered IVF success.
Luteinizing Hormone (LH) stimulates the release of eggs from the ovaries and starts the production of progesterone, a hormone that transforms the uterine environment to receive a fertilized egg. LH shows up in the urine just prior to ovulation. To help women predict ovulation before it occurs, an over-the-counter test measures increases of LH in the urine.
Just after ovulation, the ovaries produce the progesterone hormone. At about 12 to 16 days into the menstrual month, progesterone prepares the uterus for the arrival of a fertilized egg.
Progesterone levels generally peak about a week after ovulation. A physician may perform blood tests to measure the progesterone directly in the blood stream. After establishing a baseline of progesterone in the blood, a doctor will test it sometime around day 20 of the menstrual cycle. This is called a mid-luteal serum progesterone test.