Measuring Anti-Müllerian Hormone (AMH) is a common way to assess ovarian reserve, which is the remaining quantity of eggs. The AMH blood test provides data useful for family planning or fertility treatment. A frequent question is whether the results are reliable if a person is using hormonal contraception (HBC), such as the pill, implant, or ring. The influence of these synthetic hormones makes interpreting the AMH result complex. This analysis explores how HBC temporarily alters the measured AMH level.
Understanding AMH and Ovarian Reserve
Anti-Müllerian Hormone is a protein hormone produced by granulosa cells surrounding the small, developing follicles in the preantral and small antral stages. The level of AMH in the bloodstream correlates with the total number of remaining follicles in the ovary, known as the ovarian reserve.
AMH is considered one of the most reliable biomarkers for ovarian reserve because its levels remain relatively stable throughout the menstrual cycle. This stability is an advantage compared to other reproductive hormones like Follicle-Stimulating Hormone (FSH) or Luteinizing Hormone (LH), which fluctuate significantly. A higher AMH level suggests a larger remaining pool of follicles, while a lower level indicates a diminishing reserve, which naturally occurs with age.
The hormone’s role is to regulate the recruitment of primordial follicles into the growing pool. By inhibiting the initial growth of these follicles, AMH helps manage the rate at which the ovarian reserve is used up over time. Because AMH reflects the size of the pool of growing follicles, it provides an indirect estimation of the remaining egg supply.
The Impact of Hormonal Birth Control on AMH Levels
Hormonal birth control (HBC) introduces synthetic hormones that suppress communication between the brain and the ovaries. These hormones suppress the release of FSH and LH from the pituitary gland, signals necessary to stimulate follicle growth. Since AMH is produced by growing follicles dependent on these signals, suppression leads to a temporary reduction in AMH secretion.
The measured reduction in AMH levels while using HBC is a temporary physiological effect, not a permanent depletion of the ovarian reserve. Studies show that users of combined oral contraceptives may experience an AMH concentration 15% to 30% lower than non-users. Other methods, such as the vaginal ring or hormonal implant, can show similar suppression effects.
This suppression is usually reversible once the contraceptive is stopped. The synthetic hormones do not consume the actual primordial follicles, which represent the true ovarian reserve. The measured decline reflects the temporary “quieting” of the small, AMH-producing follicles.
Interpreting AMH Results While Using Contraception
If an AMH test is performed while a person is using hormonal contraception, the result must be interpreted with caution. The measured value is suppressed and does not necessarily reflect the true baseline ovarian reserve. If the AMH result is surprisingly low for the person’s age, this may be due to the temporary effect of the birth control.
If the AMH level is normal or high while on hormonal contraception, it provides reassurance that the true, unsuppressed level is likely even higher. A normal result under suppressed conditions suggests the ovarian reserve is favorable. If the measured AMH is very low, it may indicate a genuinely diminished reserve, despite the temporary suppression.
For the most accurate assessment, it is recommended to discontinue hormonal contraception and wait for a “washout” period. For short-acting methods like the pill, one to three months allows the natural hormone cycle to resume and AMH levels to rebound. Longer-acting methods, such as the contraceptive injection, may require a longer waiting time. Consulting a fertility specialist is advisable to determine the best timing for retesting and personalized interpretation.