Progestin-primed ovarian stimulation: what to know

Progestin-primed ovarian stimulation uses fertility medicines alongside a progestin to control timing during an egg-collection cycle. Gonadotrophins encourage several follicles to grow, while the progestin helps prevent an early ovulation signal. Because this approach usually leads to freezing eggs or embryos for later use rather than a fresh transfer in the same cycle, your clinic will explain the full plan.

Before treatment, the team may review ovarian reserve, cycle timing, medical history, and an AMH test alongside ultrasound findings. During stimulation, blood tests and scans assess follicle growth and hormone levels. Medication doses may be adjusted as the ovaries respond. The final maturation medicine is given when the follicles are ready, followed by egg collection at the planned time. A progestin-primed approach is different from protocols using a GnRH agonist or GnRH antagonist to control the reproductive hormone signals; your clinician chooses the method for your circumstances.

Learn the injection schedule, storage instructions, monitoring visits, and the exact time for the trigger injection. Tell the clinic about all medicines, supplements, allergies, and symptoms before starting. Contact the team if you miss a dose or cannot keep an appointment, because timing affects the cycle. Ask how eggs or embryos will be stored and what happens next; [Egg Freezing](/treatments/fertility-and-assisted-reproduction/egg-freezing/) may be the intended next step. Useful medicine terms include [Gonadotrophins](/materials/gonadotrophins/) and [hCG Trigger Injection](/materials/hcg-trigger-injection/).

Contact your fertility clinic promptly for severe or rapidly increasing abdominal swelling or pain, repeated vomiting, reduced urine, sudden weight change, or breathlessness, as these can signal ovarian hyperstimulation or another complication. Seek emergency care for severe breathing difficulty, chest pain, fainting, or one-sided leg swelling and pain. Do not wait for the next monitoring visit when symptoms are intense or progressing.

Ask why this protocol fits your ovarian reserve and treatment goal, how scans and blood tests guide dose changes, which trigger is planned, when egg collection occurs, and whether all eggs or embryos will be frozen. Ask which symptoms require a same-day call.