Top 10 facts about cycle day-3 Follicle stimulating hormone (FSH) level

1) It is generally accepted that as a woman ages, her ability to reproduce will diminish.  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) FSH level is a useful screening test of ovarian reserve.

2) Follicle stimulating hormone (FSH) 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).

3) 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 level are also routinely used (details in another blog),  Ultrasound measurement of ovarian volume and antral follicle count, patients age and weight (Body mass Index, BMI is discussed in another blog) are combined to assess ovarian reserve.

4) 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.  We have had several patients with an elevated FSH levels that have conceived on their own!!!  At InVia Fertility Specialists we do NOT use an elevated FSH level as the sole criteria to deny treatment to a patient. 

5) 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.

6) A 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.

7) 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.

8) 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.

9) 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.

10) 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”.

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.

If you have experienced trouble conceiving and live in the greater Chicagoland area, please contact InVia fertility to schedule an appointment and let us help you achieve your dreams!