Last week, we talked about how AMH may not be all that it’s purported to be. This week, I want to cover a few key factors that we know impact AMH that are not related to age.
In particular, I want to cover the top ones that I think are artificially suppressing AMH levels in many women who get their levels tested. We will save chronic conditions (e.g., PCOS, autoimmune conditions) or procedures (e.g., chemotherapy, ovarian surgery) that can impact AMH for another conversation. Today, I want to focus on the things that you can modify fairly near-term if you desire.
Vitamin D
Vitamin D deficiency has been linked to low AMH levels. Vitamin D affects AMH signaling, which means you do not necessarily have a lower egg count but impaired signaling suggests you do. Given that over half of people that we test at Poplin have Vitamin D deficiency, I think it’s safe to say that this is a factor influencing most people’s AMH results.
Hormonal birth control
Certain medications, including hormonal birth control, can artificially suppress AMH levels. Many women who are getting their AMH tested are doing so because they aren’t yet ready to have children - and therefore, many of them are on hormonal birth control. As a result, their AMH results are likely to be skewed.
One study showed that individuals on hormonal birth control had ~30% lower AMH levels, on average, than those not on hormonal birth control. Interestingly, this study also saw an impact of hormonal birth control on antral follicle count, another marker of egg quantity, as well as ovarian volume. The study concludes, “AMH concentration and AFC may not retain their accuracy as predictors of ovarian reserve in women using hormonal contraception.” If you’ve had your AMH level tested previously and were on birth control when you were tested, were you told this important caveat? The good news is that AMH levels typically recover once you discontinue hormonal birth control.
Lifestyle factors
Other studies suggest that factors such as smoking, insulin resistance, weight (both obesity and underweight) and stress may be associated with lower AMH levels.
AMH variability
Since AMH is a fairly new marker being used, there is a lot of conflicting data about it. Some researchers argue that it’s fairly stable, while others find that AMH levels fluctuate within cycles. One study found that “AMH concentrations exhibited large fluctuations throughout the cycle and did not follow a defined pattern.” These fluctuations also seemed to be larger in the younger cohort of women. Because of this, the study authors concluded that “...in younger women caution should be exerted with the interpretation of a single randomly taken AMH measurement as a representative of ovarian reserve.” In addition to fluctuating within a single cycle, AMH may also fluctuate between cycles. For example, during some months, you may have more eggs maturing (and therefore a higher level of AMH) while in other months, you may have fewer eggs maturing (and therefore lower AMH levels). Has anyone ever told you any of this before? I certainly wasn’t given these guidelines when I first tested my AMH a decade ago.
This is what we currently know, but as I keep saying, we are learning new things about AMH (and broader reproductive health) constantly as more data is collected. This is why I am such a huge fan of using broader diagnostic criteria, as well as retesting your levels over time. Using a small number of biomarkers at a single point in time to figure out what is going on with your health and fertility often misses the mark. It is important to put these markers in context with other markers to determine patterns and to retest to identify trends over time.