Anti-Müllerian Hormone (AMH) is a primary marker for ovarian reserve, widely used to assess reproductive potential. Many individuals use hormonal contraception for extended periods, leading to concerns about whether these medications influence AMH test accuracy or permanently affect the egg supply. This inquiry is relevant for anyone planning fertility assessment or considering egg freezing. This article examines the connection between hormonal birth control and AMH levels, detailing the temporary nature of any observed changes.
What Anti-Müllerian Hormone (AMH) Measures
AMH is a protein secreted by the granulosa cells surrounding the eggs within the ovarian follicles. It is produced by the small, actively growing follicles, known as pre-antral and small antral follicles, which are recruited continuously from the resting pool of primordial follicles. The level of AMH circulating in the bloodstream directly correlates with the number of these small follicles present in the ovaries.
Measuring the concentration of AMH provides an indirect but reliable estimate of an individual’s ovarian reserve, which is the quantitative aspect of the remaining egg supply. A higher AMH level generally signifies a larger reserve, while a lower level suggests a diminished pool of follicles. The decline in AMH levels over time reflects the natural, age-related decrease in the number of follicles. AMH is a measure of egg quantity, not egg quality, which is predominantly determined by age.
AMH testing has replaced older methods, such as Follicle-Stimulating Hormone (FSH) testing, as a preferred indicator because AMH levels remain relatively stable throughout the menstrual cycle. This stability makes it a convenient marker for reproductive health assessment. The hormone plays a role in regulating the rate at which resting follicles are recruited into the growing pool.
How Hormonal Contraception Affects Ovarian Function
Hormonal contraceptives (pills, patches, rings, and injections) introduce synthetic estrogen and progestin into the body. These synthetic hormones act on the hypothalamic-pituitary-ovarian (HPO) axis, the complex signaling pathway that controls the reproductive cycle. The external hormones suppress the release of gonadotropins, specifically Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH), from the pituitary gland.
The suppression of FSH is the main mechanism affecting AMH. FSH stimulates the growth and maturation of small antral follicles. By reducing FSH levels, hormonal contraception prevents the ovaries from recruiting and developing the cohort of follicles that produce AMH. This intentional ovarian suppression prevents ovulation and ensures contraceptive efficacy, but does not permanently alter the total egg reserve.
The Temporary Suppression of AMH Levels
Studies consistently show that individuals actively using hormonal contraception exhibit a measurable decrease in circulating AMH levels compared to non-users of the same age. This reduction is a consequence of the contraceptive’s mechanism of action, not a true loss of ovarian reserve. The suppression of FSH leads to fewer small follicles actively growing and producing AMH, resulting in a lower concentration of the hormone in the bloodstream.
The degree of AMH suppression can vary depending on the specific formulation of the contraceptive. Combined oral contraceptives often show a decrease ranging from 15% to 30% lower than baseline values, with some studies reporting reductions as high as 50% in long-term users. The measured AMH level while on birth control is a functional reflection of the suppressed state of the ovaries, not a direct count of the total remaining egg supply.
The clinical implication is that an AMH test performed during active use may significantly underestimate the individual’s actual, underlying ovarian reserve. A low result in this context can be misleading and cause unnecessary alarm. Since the total pool of primordial follicles remains largely unaffected, a low AMH reading while on contraception should be interpreted with caution and often necessitates retesting after discontinuation.
Recovering AMH Levels After Stopping Contraception
The inhibitory effect of hormonal contraception on AMH production is fully reversible once the medication is stopped. When the supply of synthetic hormones ceases, the HPO axis begins to re-establish its natural signaling pattern. The pituitary gland resumes its normal pulsatile release of FSH and LH, which reactivates the monthly recruitment and growth of the small antral follicles.
Consequently, the granulosa cells within these newly stimulated follicles begin producing AMH again, and the circulating AMH level rises. Research indicates that AMH concentrations typically return to the individual’s true, age-appropriate baseline within a relatively short period after stopping hormonal contraception. Most studies suggest that AMH levels stabilize within one to three menstrual cycles, or approximately two to three months. To obtain the most accurate assessment of ovarian reserve, healthcare providers recommend waiting this period before conducting an AMH test.