Egg freezing glossary

Every term you'll hear at the clinic — decoded, in plain English.

Held is peer support and education — always check anything medical with your own care team.

AMH · Anti-Müllerian Hormone

A blood test that gives a rough sense of your egg supply (ovarian reserve). Higher usually means more eggs available to stimulate — but it does not measure egg quality or predict natural fertility on its own.

Antral Follicle Count · AFC

An ultrasound count of the small resting follicles at the start of your cycle. Together with AMH it helps your clinic estimate how you might respond to the medications.

Stimulation · The "stim" phase

Roughly 8–12 days of hormone injections that encourage many follicles to grow at once (instead of the single one your body usually matures). This is the bulk of the two-week cycle.

Follicle

A small fluid-filled sac in the ovary that holds an egg. Clinics track follicle size on ultrasound to decide when your eggs are ready.

Monitoring · Monitoring appointments

Short, frequent visits (bloodwork + ultrasound) during stims so your clinic can adjust your dose and watch your follicles grow. Usually early morning, every few days, then daily near the end.

Trigger Shot

A final injection given at an exact time that matures the eggs for collection. Retrieval is scheduled ~36 hours later, so the timing really matters.

Retrieval · Egg retrieval

A ~20-minute procedure under light sedation where eggs are collected from the follicles with a thin needle guided by ultrasound. You go home the same day.

Vitrification · Flash-freezing

The modern flash-freezing method used to store eggs. It freezes so fast that ice crystals (which used to damage eggs) don’t form, which is why success rates improved so much.

OHSS · Ovarian Hyperstimulation Syndrome

An uncommon over-response to the medications causing swollen, painful ovaries. Clinics watch for it closely. Tell your team about severe bloating, pain, or rapid weight gain.

Mature (M2) Eggs · Metaphase II

Only mature eggs can be frozen for future fertilization. That’s why the count your clinic freezes can be lower than the total eggs retrieved.

Ovarian Reserve

A rough sense of how many eggs you have left. It’s estimated — not measured exactly — from AMH and your antral follicle count together. It speaks to quantity, not egg quality.

Oocyte · The medical word for an egg

You’ll see “oocyte” all over clinic paperwork and lab reports. It just means egg.

Baseline Scan

The bloodwork + ultrasound at the very start of your cycle (usually day 1–3) that checks your ovaries are “quiet” and ready before you begin injections.

Estradiol (E2) · A form of estrogen

A hormone tracked in your monitoring bloodwork. It climbs as your follicles grow, so your clinic uses it — alongside ultrasound — to judge how you’re responding and fine-tune your dose.

Protocol · Antagonist / agonist

The specific plan of medications and timing your clinic chooses for you. The common “antagonist” protocol adds a medication partway through to stop you ovulating before retrieval. There’s no one-size-fits-all — it’s matched to you.

Cryopreservation · Freezing & storing

The umbrella term for freezing and storing eggs, sperm, or embryos. For eggs, it’s done by vitrification (flash-freezing).

Thaw Survival Rate

The share of frozen eggs that survive warming when you come back to use them. It reflects the lab’s skill — a fair question to ask before you choose a clinic.

ICSI · Intracytoplasmic Sperm Injection

How frozen eggs are usually fertilized later: a single sperm is injected directly into each thawed egg. Relevant when you return to use them, not during freezing.

Egg Quantity vs Quality

Tests (AMH, AFC) estimate how many eggs you’ll get — not how healthy they are. Quality tracks most closely with age, which is why age matters more than any single number.