How Important Are AMH Levels?

Does AMH (anti-Mullerian hormone) matter? Does a low AMH, close to but under 1, mean it is not possible to conceive naturally? Any data on the chances?

—AMH Curious

This is an area that has pretty good data. AMH is not predictive of your chances of conceiving without assistance.

First, for background, AMH is produced by the small developing eggs in the ovary that potentially can be ovulated. Blood levels of AMH strongly correlate with the size of this pool, so the bigger the number of eggs, the larger the AMH level, and vice versa. Because women are born with all the eggs they ever have –– and cannot make new ones –– AMH levels naturally decrease over time as these eggs are eventually ovulated or disintegrate. At menopause, AMH levels become undetectable.

So you can see the rationale behind AMH levels being correlated with fertility; if a woman’s fertility also decreases over time, perhaps the two are related? Not necessarily.

The big thing that AMH –– and other markers of ovarian reserve, or the quantity of eggs –– is missing is a measure of egg quality, or the chances of those eggs going on and becoming healthy babies. We don’t have a test for that yet. Age is the best predictor of egg quality.

One of the best studies looking at this question is this prospective cohort study that looked at the time to pregnancy for 770 women ages 30 to 44. These were women who had been trying for three months or less, were living with a male partner, and neither partner had any known fertility problems or had ever received fertility treatment. The study authors also did not include any women who were breastfeeding or had used injectable hormonal contraception within the past year. Nonetheless, the study authors found that women with low AMH levels (< 0.7 ng/ml) had similar pregnancy rates after 6 and 12 “cycles” (menstrual cycles where ovulation is occurring) of trying, compared to women with normal AMH values.

Several other studies have all found similar results. That is not to say that AMH does not matter. AMH is most predictive of response to IVF medications. IVF meds work by targeting this pool of developing eggs, and, because human reproduction is inefficient, starting with higher numbers increases your chances.