Hormonal birth control methods introduce synthetic hormones into the body, which significantly influence the natural reproductive system. Understanding how these synthetic hormones interact with the body’s own hormone production is important for interpreting fertility test results. This article will clarify how fertility tests interact with birth control use.
How Birth Control Affects Fertility Markers
Hormonal birth control primarily works by suppressing ovulation. These contraceptives typically contain synthetic versions of estrogen and/or progesterone, known as progestin. The presence of these synthetic hormones alters the balance of natural reproductive hormones.
By suppressing ovulation, hormonal birth control directly impacts the levels of hormones measured in fertility assessments. For example, estrogen can suppress the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), both of which are necessary for the development and maturation of follicles in the ovaries. This suppression effectively masks the body’s natural fertility signals, making it difficult to get an accurate reading of baseline hormone levels.
Hormonal contraception also thickens cervical mucus, making it harder for sperm to reach the uterus, and thins the uterine lining, which can prevent a fertilized egg from implanting. These changes are designed to prevent pregnancy and mean that the body is not operating under its natural reproductive cycle. Thus, hormonal measurements taken while on birth control will reflect the influence of the synthetic hormones rather than the body’s inherent fertility status.
Fertility Tests and Their Accuracy While on Birth Control
Several fertility tests are significantly affected by hormonal birth control, making their results inaccurate. Hormonal blood tests, such as those for FSH, LH, estradiol (E2), progesterone, and Anti-Müllerian Hormone (AMH), are generally not accurate while on hormonal contraception. This is because the synthetic hormones in birth control suppress the pituitary gland’s gonadotropins (FSH and LH) and alter estrogen and progesterone levels, preventing the natural menstrual cycle from occurring. For instance, AMH levels, which indicate ovarian reserve, can be temporarily lowered by hormonal birth control.
Ovulation tracking methods, including urine ovulation predictor kits (OPKs) and basal body temperature (BBT) charting, are not reliable. OPKs detect the LH surge that precedes ovulation, but since hormonal birth control suppresses ovulation, this surge typically does not occur naturally. Similarly, BBT changes are linked to the natural hormonal fluctuations of the menstrual cycle, which are disrupted by contraception.
However, some tests can still provide valuable information while on birth control. Structural tests, such as pelvic ultrasounds, can assess the uterus and ovaries for conditions like fibroids, polyps, ovarian cysts, or structural abnormalities. These physical structures are not directly altered by hormonal birth control. A hysterosalpingogram (HSG), which checks the patency of the fallopian tubes by injecting a contrast dye, also remains an accurate assessment of tubal blockages. These tests evaluate physical aspects of the reproductive system rather than hormonal function. A male partner’s semen analysis, which assesses sperm count, motility, and morphology, is entirely unaffected by the female partner’s birth control use.
Planning for Accurate Fertility Testing
For comprehensive and accurate fertility testing, it is generally necessary to discontinue hormonal birth control. Healthcare providers and fertility specialists recommend stopping hormonal contraception for a period to allow the body’s natural hormonal cycle to re-establish itself. The exact duration for this “washout” period can vary, often ranging from a few weeks to several months, depending on the type and duration of birth control used.
For instance, while fertility can return quickly after stopping some birth control methods, it may take up to 12 months for menstrual cycle hormones to regulate after long-term use of a contraceptive injection. This waiting period allows the body to resume its natural production of FSH, LH, estrogen, and progesterone, which are crucial for obtaining meaningful results from hormonal fertility tests. Consulting with a healthcare provider or fertility specialist is important to determine the appropriate timing and specific tests based on individual circumstances and medical history.