Anti-Müllerian Hormone (AMH) is a primary diagnostic tool used by doctors to assess a woman’s reproductive potential. This hormone provides an estimate of the remaining egg supply, commonly referred to as the ovarian reserve. Because hormonal birth control is a widely used medication, a common question arises regarding whether this medication interferes with AMH testing accuracy. The reliability of an AMH measurement taken while a patient is actively using hormonal contraceptives is a subject of discussion among fertility experts. This article examines the function of AMH, the specific effect of hormonal methods on its levels, and the protocols necessary for obtaining a truly accurate reading.
Understanding AMH and Ovarian Reserve
Anti-Müllerian Hormone is a substance produced by the granulosa cells that surround the smallest, growing egg follicles within the ovaries. The level of AMH found in the bloodstream is thought to correlate directly with the size of the remaining pool of these early-stage follicles. This pool represents the ovarian reserve, or the total quantity of eggs remaining in the ovaries.
Doctors use AMH levels as a quantitative indicator of this reserve, helping to predict how a patient might respond to fertility treatments such as In Vitro Fertilization (IVF). A higher level of AMH generally suggests a greater number of follicles available for stimulation. Conversely, a lower level indicates a diminished reserve, which can also help in estimating the timeline toward menopause. The AMH test is valued because its levels remain relatively stable throughout the menstrual cycle, unlike other reproductive hormones. However, AMH primarily reflects egg quantity and is not a definitive predictor of the ability to conceive naturally.
How Hormonal Contraception Affects AMH Levels
Hormonal contraceptives, including the pill, patch, ring, and injection, introduce synthetic hormones into the body to prevent pregnancy. These exogenous hormones suppress the production of gonadotropins, specifically Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH), from the pituitary gland. This suppression subsequently dampens the development of the small ovarian follicles that are responsible for AMH production.
Multiple studies have shown that women actively using hormonal contraception can have significantly lower AMH levels compared to age-matched women who are not. For instance, the combined oral contraceptive pill may result in AMH readings that are approximately 17% to 23.7% lower than the natural baseline. This temporary reduction in the hormone’s concentration is a direct consequence of the medication’s mechanism of action.
This measured suppression, however, does not signify a permanent loss or damage to the actual ovarian reserve. The hormonal medication simply masks the true level by temporarily lowering the active production of the hormone. Once the medication is discontinued, the reproductive system typically resumes its natural cycle, and AMH levels are expected to rebound to their true, unsuppressed baseline. The degree of suppression can vary based on the specific type of contraception used, with combined pills, implants, and rings generally showing a greater impact than progestin-only methods or hormonal intrauterine devices (IUDs).
Accurate Testing Protocols
To obtain a truly accurate measurement of the ovarian reserve that is not obscured by medication, a “washout period” is generally advised after stopping hormonal contraception. The goal of this break is to allow the body’s natural hormone production to fully restart and stabilize.
For many forms of short-acting hormonal contraception, such as the pill, patch, or ring, experts commonly recommend a waiting period of two to three full menstrual cycles, or approximately 60 to 90 days. This timeframe ensures that the synthetic hormones have completely cleared the system and the ovaries have returned to their normal, cycling function. For long-acting methods, such as the contraceptive injection, a longer washout period may be necessary before reliable testing can occur.
AMH levels are expected to return to the individual’s true baseline once the hormonal suppression is lifted. If an AMH test is performed while on birth control and the result is unexpectedly low for the patient’s age, a re-test after the recommended washout period is strongly advised to confirm the true ovarian reserve.