FSH (Follicle Stimulating Hormone) –
What is it? FSH is a hormone which is released from the pituitary gland to stimulate the ovaries. The higher the level of FSH, the harder the pituitary is working to get the ovaries to respond, indicating poor egg quality or low ovarian reserve.
Normal range? Ideally FSH levels should be 10 or less (optimal being under 6) on cycle day 3. A common misconception is that women with high FSH cannot become pregnant. FSH levels can fluctuate from month to month, and be elevated for reasons unrelated to ovarian reserve, such as ovarian cysts.
LH (Luteinizing Hormone) –
What is it? LH is a hormone released from the pituitary to support formation of the corpus luteum and ovulation. LH that is too low or too high can be problematic for fertility, indicating anovulation, polycystic ovaries or pituitary disease. LH spikes about 48 hours prior to ovulation so can be helpful in prediction ovulation in some women.
Normal range? LH should be <7 mlU/ml on day 3, and during the pre-ovulation surge spikes to >20 mlU/ml.
Estradiol
What is it? The primary form of estrogen responsible for female reproduction and menstruation. Estradiol is made in the ovaries, and when combined with FSH levels help to predict egg quality and ovarian reserve. High levels of estrogen can indicate functional ovarian cysts or poor ovarian reserve, and can suppress FSH levels. Women undergoing fertility treatments who have high day 3 estradiol do not respond as well to ovarian stimulants and have poorer IVF outcomes.
Normal range? Optimal range (day 3) is below 80 pg/ml or 294 pmol/L.
Progesterone
What is it? Progesterone is a hormone secreted by the corpus luteum once ovulation has occurred. Progesterone should peak between 5-9 days post 
ovulation, so is typically tested 7 days post ovulation to confirm ovulation and determine if levels are supportive of implantation.
Normal range? Best tested 7 days post ovulation (day 21 in women with a 28 day cycle), and a level of >30 nmol/L is optimal.
Prolactin
What is it? Prolactin is a hormone secreted by the pituitary gland, and if elevated can inhibit ovulation and prevent pregnancy. Prolactin is naturally high in women who are breastfeeding, and abnormally high levels could indicate a pituitary tumour.
Normal range? Less than 24 ug/L
