Testosterone does not permanently make you infertile in most cases, but it does significantly suppress your reproductive system while you’re taking it. The key distinction: testosterone reliably stops ovulation and periods for most trans men, yet this suppression appears to be reversible when testosterone is discontinued. At the same time, testosterone is not reliable birth control, and pregnancies have occurred in trans men actively on T.
This creates a confusing middle ground. You’re less fertile on testosterone, but not predictably so, and the long-term picture is more reassuring than many people expect.
How Testosterone Suppresses Fertility
Your body’s reproductive system runs on a feedback loop between your brain and your ovaries. The hypothalamus and pituitary gland release signaling hormones (LH and FSH) that tell your ovaries to mature eggs and ovulate. When you introduce exogenous testosterone, it disrupts this loop. Your brain detects elevated hormone levels and dials back its own signals.
Research on this suppression shows it happens relatively quickly. At moderate to high doses, LH and FSH become undetectable within two to six weeks of starting testosterone. Without those signals, your ovaries stop releasing eggs, and menstruation typically stops. For most trans men, periods cease within the first few months of therapy.
But “suppressed” is not the same as “destroyed.” The system is being held in a dormant state, not dismantled. When testosterone is discontinued, the signaling hormones return, and ovulation can resume. This reversal has been documented repeatedly in clinical settings, though the exact timeline varies from person to person.
Ovarian Reserve Stays Largely Intact
One of the biggest concerns for trans men considering future biological children is whether years of testosterone will damage their egg supply. The evidence so far is reassuring. A study of 47 trans men who had been on testosterone for a median of nearly three years found that their ovarian reserve, measured by both egg-related hormone levels and follicle counts on ultrasound, remained within the normal range for their age. The marker most closely tied to egg supply did not correlate with how long someone had been on testosterone. It correlated with age, just as it does in the general population.
In a prospective portion of that research, there was a slight dip in ovarian reserve markers during the first year of testosterone, but the values stayed within normal limits. The one group that showed a more noticeable decline was trans men who also had polycystic ovary syndrome (PCOS), a condition that independently affects ovarian function. For those without PCOS, the follicle count didn’t change significantly over 12 months of treatment.
The researchers concluded that prolonged testosterone treatment “may not be a major obstacle to later fertility potential in transgender men desirous of having children.” This aligns with what the Endocrine Society notes in its clinical guidelines: pregnancies have been reported in trans men who used testosterone for extended periods, stopped, and conceived without surgical intervention.
Testosterone Is Not Birth Control
This is the flip side, and it catches some people off guard. Even if your periods have stopped completely, you can still ovulate unpredictably while on testosterone. The Canadian Medical Association Journal has noted that trans men with a uterus experience unplanned pregnancies at rates similar to cisgender women. The CDC states plainly that testosterone therapy “has not been studied as contraception” and should not be relied on to prevent pregnancy.
If you’re having sex that could result in pregnancy and you don’t want to become pregnant, you need a separate method of contraception. The evidence on which hormonal contraceptives are safe to combine with testosterone is limited, but progestin-only options (like hormonal IUDs or the implant) are commonly discussed because they don’t contain estrogen, which could interfere with masculinization. Barrier methods work too. The important thing is not assuming that amenorrhea (lack of periods) equals infertility.
Fertility Preservation Options
If biological children might matter to you in the future, the standard recommendation from both WPATH and the Endocrine Society is to discuss fertility preservation before starting testosterone. Egg or embryo freezing is ideally done before hormone therapy begins, since the process requires ovarian stimulation, which temporarily raises estrogen levels and can feel physically and emotionally uncomfortable for trans men.
That said, “ideally before” doesn’t mean “only before.” Trans men who are already on testosterone can pause therapy to undergo egg retrieval. Traditionally, this has meant stopping testosterone for three to six months, or until menstruation returns. The wait can be distressing, and it’s one of the biggest barriers to fertility preservation in this population.
More recently, there’s emerging clinical experience with shorter cessation periods. At least one published case demonstrated successful ovarian stimulation in a trans man without prolonged testosterone cessation and without waiting for periods to return. No professional guidelines yet specify exactly how long you need to stop testosterone before egg retrieval, which means practice varies between clinics. If you’re considering this route, it’s worth finding a reproductive endocrinologist experienced with transgender patients.
What We Don’t Fully Know Yet
The honest picture includes some gaps. Most studies on ovarian reserve in trans men involve relatively young participants (median age in the mid-20s) who used testosterone for a few years. Data on people who started testosterone as teenagers, or who’ve been on it for 15 or 20 years, is sparse. The Endocrine Society describes the effect of prolonged testosterone on ovarian function as “uncertain,” even while acknowledging that successful pregnancies after long-term use have been documented.
There’s also limited data on egg quality after testosterone use, as opposed to egg quantity. Ovarian reserve markers tell you roughly how many follicles remain, but they don’t fully predict whether those eggs will result in a healthy pregnancy. The existing pregnancy reports are encouraging, but large-scale outcome studies haven’t been done yet.
For trans men who went directly from puberty blockers to testosterone without experiencing a full natural puberty, the fertility picture is even less clear. The eggs may never have been exposed to the hormonal environment that typically matures them, and there’s very little data on retrieval outcomes in this specific group.
The Practical Takeaway
Testosterone puts your reproductive system on pause, but the current evidence suggests it doesn’t permanently shut it down. Your ovarian reserve appears to hold up over years of treatment, and fertility can return after stopping. At the same time, the suppression is unreliable enough that pregnancy can happen while you’re actively on T, so contraception matters if pregnancy is something you want to avoid. If future biological children are important to you, freezing eggs before starting testosterone is the most straightforward path, but it’s not your only window.