1) It is generally accepted that as a woman ages, her ability to reproduce will diminish and she will begin having trouble getting pregnant.
It is generally accepted that as a woman ages, her ability to reproduce will diminish and she will begin having trouble getting pregnant. There, however, is a wide range as to the age at which a woman’s ovarian reserve (reproductive potential) will diminish. Some women progress through menopause in their early thirties, while others conceive readily at age 45. A basal (cycle day 2 – 4) follicle stimulating hormone (FSH) level is a useful screening test of ovarian reserve.
Follicle stimulating hormone is the hormone released by the pituitary gland in the brain to stimulate the ovary to produce an egg. A “good” quality egg, in turn, releases certain hormones (inhibin, estradiol), which will lower (negative feedback) the FSH level. If the egg quality is compromised, the negative feedback signals are weak and there is a rise in the FSH level. An elevated FSH level therefore suggests that the reproductive potential of the woman’s eggs is compromised (diminished ovarian reserve).
Ovarian reserve screening is generally done on day 2, 3 or 4 of the menstrual cycle. In addition to an FSH level, we will usually measure luteinizing hormone (LH) and estardiol (E2) levels. Anti-mullaerian hormone levels are also routinely used (details in another blog), Ultrasound measurement of ovarian volume and antral follicle count, patient's age and weight (body mass Index, BMI is discussed in another blog) are combined to assess ovarian reserve.
There is no single “normal” value for a basal FSH level. The value varies from clinic to clinic and varies based on the assay used. At InVia Fertility Specialists, we like the FSH level to be < 10 mIU/mL. A value between 10 and 15 mIU/mL signifies diminished ovarian reserve. A value > 15 mIU/mL (and definitely > 20 mIU/mL) signifies severely diminished ovarian reserve and a pregnancy rate with IVF of < 1%.
An elevated FSH level does not rule out the possibility of a spontaneous pregnancy. InVia Fertility Specialists has had several patients with elevated FSH levels who have conceived on their own! We do NOT use an elevated FSH level as the sole criteria to deny treatment to a patient.
FSH is released in a pulsatile manner by the pituitary. There is therefore a wide variation in the basal FSH level from one cycle to another (inter-cycle variability). Generally, the highest FSH level is the most predictive of ovarian reserve.
An FSH level has a low sensitivity level in predicting diminished ovarian reserve. What this means is that some women with a “normal” FSH level will have diminished ovarian reserve.
Age is a better predictor of diminished ovarian reserve than FSH. A 45-year-old will have a reduced fertility potential even if her FSH level is normal.
Younger patients with an elevated FSH level have a better prognosis than older patients with an elevated FSH level. In young patients with high FSH level, we will often recommend aggressive treatment (e.g. IVF) early in the treatment plan.
An elevated FSH level does predict the chance of pregnancy. However, it does not predict ovarian response to fertility drugs. A patient with a high FSH level may respond normally to ovarian stimulation. Other parameters like antral follicle counts and anti-mullerian hormone (AMH) levels are better predictors of ovarian response.
Along with the FSH level, we will usually draw an estradiol (E2) level. Generally, the E2 level should be less than 100 pg/mL. An E2 level can be elevated due to the presence of a cyst. We therefore will do an ultrasound along with blood tests at the time of screening. An elevated basal E2 level (> 100 pg/mL) in the absence of a cyst could be a sign of diminished ovarian reserve. A high E2 level will in turn suppress the FSH level, which will then appear to be falsely “normal”.
What Happens If Your FSH Level is Elevated?
If your day-3 FSH level is elevated, the next step is to have a discussion with your physician. A combination of age, FSH, E2, AMH level, antral follicle count, weight and previous ovarian response will probably used to estimate your chances of success.
Dr. Karande is Board Certified in the specialty of Obstetrics and Gynecology as well as the subspecialty of Reproductive Endocrinology and Infertility. He is a Fellow of the American College of Obstetricians and Gynecologists and Member of the American Society for Reproductive Medicine.