IVF Protocols Explained (UK guide)

When you start IVF, one of the first decisions your clinic makes is choosing your stimulation protocol — the medication schedule used to grow follicles, collect eggs, and prepare for fertilisation. But most patients find IVF protocols confusing, and clinics rarely explain why they pick one over another. This guide provides a clear, simple overview of the most common IVF protocols used in the UK, who they're recommended for, and what to expect. What Is an IVF Protocol? An IVF protocol is the medication strategy used to stimulate the ovaries and control ovulation timing. It determines: How long the cycle lasts Which medications you take How many eggs you're likely to produce How your body responds Different people need different protocols depending on: Age Ovarian reserve (AMH, AFC) Previous IVF responses PCOS Endometriosis Male factor issues Clinic preference The 5 Main IVF Protocols Used in the UK 1. Antagonist Protocol (Most Common in the UK) Who it's for: Most first-time IVF patients Women under 40 Normal responders PCOS (reduced OHSS risk) How it works: You start stimulation on Day 2–3 and add an antagonist injection mid-cycle to prevent premature ovulation. Pros: Flexible Lower risk of OHSS Shorter cycle Widely used Cons: May produce fewer eggs in low responders 2. Long Protocol (Downregulation Protocol) Who it's for: Younger women Endometriosis Fibroids People needing more