In short
Follicle-stimulating hormone (FSH) is a natural fertility hormone used to stimulate egg development in assisted reproduction. One authorised Phase 3 trial (2026-526292-37-01) is testing whether adding follitropin delta to standard ovulation triggering increases the number of mature eggs in 126 women with low ovarian reserve undergoing IVF with fresh embryo transfer.
Key points
- Follicle-stimulating hormone is a glycoprotein hormone that acts on the follicle-stimulating hormone receptor (FSHR) in the ovaries.
- One Phase 3 clinical trial is authorised in the EU, planning to enrol 126 women with infertility and low ovarian reserve.
- The trial compares three methods of triggering ovulation in IVF treatment with fresh embryo transfer.
- The main measure is the number of mature (MII) oocytes retrieved at egg collection.
- All study drugs are given by subcutaneous injection.
- The trial status is Authorised, meaning it has received regulatory approval to begin.
What is follicle-stimulating hormone?
Follicle-stimulating hormone (FSH) is a glycoprotein polypeptide hormone belonging to the gonadotropin family, which also includes luteinizing hormone (LH), thyroid-stimulating hormone (TSH), and chorionic gonadotropin (CG). FSH is secreted by the anterior pituitary gland, a small gland at the base of the brain. In the clinical trial registry, the substance appears under the name follitropin delta, which is a recombinant form of FSH used in fertility treatment.
How does follicle-stimulating hormone work?
FSH acts by binding to the follicle-stimulating hormone receptor (FSHR), a protein found on the surface of cells in the ovaries. Activating this receptor stimulates the growth and maturation of ovarian follicles, the small sacs in the ovary that contain developing eggs. In fertility treatment, giving FSH from outside the body aims to encourage several follicles to develop at once, so that more mature eggs can be collected for in vitro fertilisation (IVF).
Which conditions is it used or studied for?
- Infertility with low ovarian reserve — the authorised Phase 3 trial studies women who have a reduced number of eggs available in their ovaries, which can make it harder to become pregnant.
- Fertility disorders — research on the FSH receptor describes FSH as a biological target for treating fertility disorders more broadly.
How is follicle-stimulating hormone given?
In the authorised trial, follitropin delta is given as a solution for injection in a pre-filled pen, administered by subcutaneous injection under the skin. The trial also uses other injectable fertility medicines, including ganirelix (Orgalutran), triptorelin (Decapeptyl diario), choriogonadotropin alfa (Ovitrelle), and menotrophin (Meriofert Kit), all given subcutaneously.
What do the clinical trials show?
One Phase 3 interventional trial is authorised in the EU under the number 2026-526292-37-01. The trial plans to enrol 126 women with infertility and low ovarian reserve. It compares three methods of triggering ovulation in IVF treatment with fresh embryo transfer: adding follitropin delta to hCG ovulation triggering, and two other approaches using the listed injectable medicines.
The primary outcome is the number of metaphase II (MII) oocytes retrieved at oocyte pickup — in plain words, how many mature eggs are collected from the ovaries. The trial is currently in the Authorised status, meaning it has received regulatory approval and can begin recruiting participants.
What side effects are known?
The provided supplementary source does not report side effects for follicle-stimulating hormone or follitropin delta. Therefore, no side effect information is included on this page.