Antimüllerian hormone levels are associated with time to pregnancy in a cohort study of 3,150 women

Abstract

Objective: To study the association between antimüllerian hormone (AMH) levels and time of pregnancy. Although it has been hypothesized that serum AMH levels may indicate the chance of conception, findings have been mixed. Given that any association is expected to be modest, and it is possible that previous studies have been underpowered, we investigated this relationship in the largest prospective cohort to date.

Design: Prospective time-to-pregnancy cohort study.

Setting: Community.

Patient(s): A total of 3,150 US women who had been trying to conceive for <3 months and had purchased a Modern Fertility hormone test.

Intervention(s): We developed a discrete time-to-event model using a binomial complementary log-log error structure within a generalized additive modeling framework, adjusting for confounding factors such as age, body mass index, parity, smoking status, polycystic ovary syndrome, and others. Sensitivity analyses were performed in women with regular menstrual cycles (21-35 days), who did not report using fertility treatments, using alternate AMH level categories (<0.7, 0.7-8.5, >8.5 ng/mL), and AMH levels as a continuous measure.

Main outcome measure(s): Primary outcomes included cumulative conception probability within 12 cycles and relative fecundability per menstrual cycle. Conception was defined by a self-reported positive pregnancy test.

Result(s): Participants contributed 7.21 ± 5.32 cycles, with 1,325 (42.1%) achieving a pregnancy. Women with low AMH levels (<1 ng/mL, n = 427) had a lower chance of natural conception (adjusted hazard ratio [adjHR], 0.77; 95% confidence interval [CI], 0.64-0.94) compared with women with normal AMH levels (1-5.5 ng/mL). There was no difference between high (5.5+ ng/mL) and normal AMH level categories (adjHR, 1.11; 95% CI, 0.94-1.31). The inclusion of AMH improved the model (net reclassification index 0.10 [0.06-0.14]). The instantaneous probability of conception was highest in cycle four across all AMH categories: the probability of natural conception was 11.2% (95% CI, 9.0-14.0) for low AMH levels, 14.3% (95% CI, 12.3-16.5) for normal AMH levels, and 15.7% (95% CI, 12.9-19.0) for high AMH levels. In the regular cycles sensitivity analysis (n = 1,791), the low AMH group had a lower chance of conception (adjHR, 0.77; 95% CI, 0.61-0.97) in the low AMH group compared with normal AMH, and similarly in the continuous model (adjHR, 0.90; 95% CI, 0.85-0.95).

Conclusion(s): Low AMH levels (<1 ng/mL) are independently associated with a modest but significant reduction in the chance of conception.

Keywords: AMH; conception; fecundity; ovarian reserve; pregnancy.