Low anti-Müllerian hormone level may lessen likelihood of natural conception

NEW ORLEANS — Women with lower levels of anti-Müllerian hormone may take longer to become pregnant naturally, without use of assisted reproductive technologies, than their same-age peers with higher levels, according to a speaker.

“It’s long been accepted that [anti-Müllerian hormone] is not informative when it comes to the chances of becoming pregnant outside of [assisted reproductive technologies],” Sharon Briggs, PhD, director of research and clinical strategy at the digital health company Ro, told Healio. “That we are able to see a robust association among women who are trying to conceive outside of a fertility clinical setting has a chance to seriously challenge this long-held belief.”

Earlier smaller studies suggested that anti-Müllerian hormone (AMH) was likely to have only a moderate effect on likelihood of natural conception, Briggs said during a presentation at the ASRM Scientific Congress & Expo. Briggs and colleagues explored the relationship with a larger group of women using at-home fertility tests.

The researchers analyzed data from 3,150 women trying to conceive for less than 3 months who used a hormone test (Modern Fertility) and opted in to data collection for this study, according to Briggs. In the study population, mean AMH was 2.71 ng/mL, mean age when they started trying to conceive was 31.5 years, mean BMI was 25 kg/m², 4.3% reported smoking, 74% said they had never been pregnant, 6.1% had polycystic ovary syndrome, and 5.8% reported use of assisted-conception technologies.

The researchers categorized participants’ AMH levels as low (< 1 ng/mL; n = 427), normal (1 ng/mL to 5.5 ng/mL; n = 2,219) or high (> 5.5 ng/mL; n = 504).

After adjusting for age, BMI, parity, smoking status and PCOS, among other factors, the women with low AMH had a 23% lower likelihood of natural conception compared with women with normal levels (adjusted HR = 0.77; 95% CI, 0.64-0.94; P = .009). Women with low AMH had lower likelihood of conception during 12 menstrual cycles compared with women with normal levels. No difference in likelihood of natural conception was observed for those with normal and high AMH levels.

Among the 1,791 women with regular menstrual cycles, those with low AMH still had lower likelihood of natural conception than those with normal levels (aHR = 0.77; 95% CI, 0.61-0.97; P = .028).

“We show a robust association between AMH levels and the chance of natural conception. When AMH is less than 1 ng/mL, we see an association with a slightly longer time to pregnancy compared to normal AMH, meaning those with low AMH take longer to conceive, on average, when compared to those with a normal AMH, even if they are the same age,” Briggs told Healio.

Among women with regular menstrual cycles, the highest probability of natural conception was in the second month of the study and increased as AMH level increased.

“These findings suggest that measuring AMH levels in those seeking preconception advice can be an informative part of a comprehensive explanation of factors influencing the likelihood of natural conception,” Nelson said. “We believe that this is useful data to encourage people with ovaries to understand their AMH level to better their fertility.”