AMH and Antral Follicle Count: A Clinician's Guide to Ovarian Reserve Testing

Ovarian reserve testing is now part of almost every infertility workup. Used well, it helps clinicians plan ovarian stimulation and counsel couples realistically. Used poorly, it causes unnecessary anxiety and rushed decisions. This guide covers what anti-Müllerian hormone (AMH), antral follicle count (AFC) and basal FSH actually measure, and how to use them in practice.

What "ovarian reserve" means

Ovarian reserve refers to the size of the remaining pool of follicles. The tests below estimate the quantity of oocytes a woman is likely to produce in response to stimulation. They say very little about oocyte quality, which is driven mainly by age.

Anti-Müllerian hormone (AMH)

AMH is produced by granulosa cells of small growing follicles. It is a useful marker because:

• It can be measured on any day of the cycle, with relatively small cycle-to-cycle variation
• It correlates well with the number of oocytes retrieved after stimulation
• It helps predict poor and excessive response to gonadotropins

Points to remember:

• Assays differ. Results from different AMH assays are not directly interchangeable, so interpret against the reference ranges of the laboratory used
• Hormonal contraception and vitamin D status can lower measured AMH; repeat testing after stopping the pill may be appropriate
• PCOS is associated with high AMH, which can signal a risk of excessive response
• AMH does not predict natural conception in women without a diagnosis of infertility, and should not be offered as a "fertility test" for the general population

Antral follicle count (AFC)

AFC is the number of follicles measuring about 2 to 10 mm in both ovaries, counted on transvaginal ultrasound, usually in the early follicular phase (day 2 to 5).

• It gives an immediate result alongside the baseline scan
• It correlates closely with AMH and with oocyte yield
• It depends on operator skill and equipment, so units should standardise how they count and record follicles

Basal FSH and estradiol

Day 2 to 3 FSH was the traditional test, but it varies considerably between cycles and becomes abnormal only late in the decline of ovarian reserve. A high basal FSH is meaningful, but a normal value does not rule out low reserve. Estradiol should be measured alongside FSH, because an early rise in estradiol can suppress FSH and make it look falsely reassuring.

Using results to plan stimulation

Ovarian reserve markers are most useful for individualising the stimulation protocol and gonadotropin dose:

• Predicted high responders (high AMH or AFC, PCOS): consider an antagonist protocol, cautious dosing and a GnRH agonist trigger to reduce the risk of OHSS
• Predicted normal responders: standard dosing according to unit protocols
• Predicted poor responders: counsel about expected oocyte numbers; note that increasing the gonadotropin dose beyond a certain level has not been shown to improve live birth rates

Classifications such as the Bologna criteria and the POSEIDON groups help define poor responders consistently and compare outcomes. For more on protocols, see our article on antagonist versus agonist stimulation protocols.

Common mistakes in interpretation

• Treating a single low AMH value as proof of infertility
• Using AMH to "time" conception in women not trying to conceive
• Ignoring age: a 30-year-old and a 42-year-old with the same AMH have very different prospects because of oocyte quality
• Comparing AMH values across different laboratories without accounting for the assay

Counselling couples

Explain that ovarian reserve tests predict how the ovaries are likely to respond to medication, not whether a pregnancy will happen. Discuss results together with age, duration of infertility, semen analysis and tubal status. Under India's ART (Regulation) Act, 2021, informed consent and clear written counselling are required before ART procedures, so documenting this discussion is good practice as well as a legal requirement.

Frequently asked questions

Can AMH be tested on any day of the cycle?

Yes. AMH varies relatively little through the menstrual cycle, so it can be measured on any day. AFC, by contrast, is usually counted in the early follicular phase.

Does a low AMH mean a woman cannot conceive?

No. A low AMH suggests fewer oocytes will be retrieved with stimulation, but it does not predict natural conception on its own. Age and oocyte quality remain the main determinants of outcome.

Which is better, AMH or AFC?

Both predict ovarian response with similar accuracy. AMH is a lab test that is less operator-dependent, while AFC gives an immediate ultrasound result. Many clinicians use both together.

Learn ovarian stimulation planning hands-on

The Fellowship in Reproductive Medicine & Infertility Management covers infertility assessment, endocrine workup and individualised stimulation planning. Read about the skills every fertility specialist needs, or contact our team for batch details.

This article is educational content for healthcare professionals and trainees. It is not medical advice and does not replace clinical judgement, current guidelines or the ART (Regulation) Act 2021 and Rules 2022.