Low AMH levels linked to reduced chance of conception

Low levels of anti-Müllerian hormone (AMH) decrease the chances of becoming pregnant, independently of age or duration of time spent trying to conceive.

Although at-home fertility tests have soared in popularity, their reliance on AMH levels as an accurate fertility indicator has been debated in the literature. In the largest prospective cohort to date, researchers at the University of Glasgow School of Medicine and Department of Medical Physics investigated the link between AMH and time to pregnancy.

'We identify that a low AMH is negatively associated with time to pregnancy... women with an AMH level <1 ng/ml will take approximately 20 percent longer to conceive,' the authors wrote in the journal Fertility and Sterility.

The study participants were customers of Modern Fertility – an at-home fertility kit developed in San Francisco, California. The cohort of 3150 women were between the ages of 21 and 45, with a median age of 31.5, had regular menstrual cycles (21-35 days), and had been trying to conceive naturally for fewer than three months.

Between 2018 and 2023, participants tracked their menstrual cycles in the Modern Fertility app and collected their blood on the third day to send for analysis.

Over the course of 12 or fewer cycles, self-reported pregnancy occurred in 44 percent of women with normal AMH levels, compared with just 31 percent of women with low AMH levels. This association fits with other AMH trends reported (see BioNews 1274 and 1136).

Women who reported pregnancy were also more likely to not have polycystic ovary syndrome, have a lower body mass index, and be younger. Across all AMH categories, women had the greatest chance of conceiving in cycle four.

Though these data are statistically significant, at-home blood draws, cycle tracking, and self-reported pregnancies leave more room for error than hospital-based trials.

Additionally, there may have been a socioeconomic selection bias for wealthier women who could afford the fertility kit, and the majority of participants with known demographics were white. Information on male partners was also unknown, as well as data on miscarriages.

However, this study supports the use of AMH levels in fertility tests to screen for those who may need early interventions. The authors wrote, 'Although AMH level declines with age, for young women with inappropriately low AMH level this may reflect more rapid ovarian ageing and with that, a higher risk of early menopause.'