About Fertility

FSH, LH & Estradiol Hormones


FSH, or follicle stimulating hormone, and estradiol, a form of estrogen, are two hormones routinely measured during fertility testing to assess ovarian reserve, or the potential of the ovaries to recruit healthy eggs. These hormones are measured on day 3 of the menstrual cycle (remember: day 1 is first day of full flow!).

What is FSH?

FSH is a hormone produced by the pituitary gland in the brain. It stimulates the growth of early (“antral”) follicles in the ovaries. On day 3, a normal FSH is less than 10IU/ml. A higher FSH on day 3 means that the body is working harder to induce follicular growth.

What is Estradiol?

Estradiol is a hormone produced by the granulosa cells of growing follicles. On cycle day 3, estradiol levels are typically less than 50pg/ml. A “dominant” follicle produces the most estradiol, typically growing to greater than 20mm before ovulation, while the others become atretic (die off). Estradiol levels reach 200-400pg/ml during a normal cycle and drop after ovulation. Estradiol also stimulates thickening of the endometrial lining during the follicular phase.

What is LH?

LH, or luteinizing hormone, is another hormone produced by the pituitary gland. It plays an important role in preparing follicles to produce estradiol, and it “surges” prior to ovulation. Your physician may measure an LH level on day 3 as well. LH is typically less than 10 IU/L at this time, though some women, such as those with PCOS, may have higher baseline LH levels.

We know it can be overwhelming learning about and understanding the female hormones. We’re here to walk you through any questions you may have. Schedule your appointment with the Fertility Centers of New England today!

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