Fertility isn’t a single yes-or-no status. It depends on two things: whether you’re ovulating regularly and whether your body (and your partner’s, if applicable) can support conception. Some signs you can track at home with no tools at all, while others require blood work or imaging. Here’s how to read the signals your body is already giving you, and when testing can fill in the gaps.
Your Cervical Mucus Is the Simplest Clue
The most immediate, no-cost way to gauge fertility is to pay attention to your cervical mucus throughout your cycle. In the days right before ovulation, your body produces mucus that looks and feels like raw egg whites: clear, slippery, and stretchy between your fingers. This type of mucus keeps sperm alive longer and helps them travel toward the egg.
Earlier in your cycle, mucus tends to be sticky, white, or pasty, or you may not notice much at all. As you approach ovulation (typically around days 10 to 14 of a 28-day cycle), it transitions to that wet, stretchy consistency. Once you see it, you’re likely in your most fertile window. After ovulation, mucus dries up or becomes thick again. If you notice this egg-white pattern regularly each month, it’s a strong sign that you’re ovulating.
Tracking Your Temperature After Ovulation
Basal body temperature (BBT) is your resting temperature first thing in the morning, before you get out of bed. After you ovulate, rising progesterone causes a small but measurable temperature shift, typically less than half a degree Fahrenheit (about 0.3°C). You need a thermometer that reads to two decimal places to catch it.
The key pattern is a “biphasic” chart: lower temperatures in the first half of your cycle, then a sustained rise in the second half. That shift confirms ovulation already happened, so it won’t tell you the best day to conceive in real time. But tracking over two or three months reveals whether you’re ovulating consistently. If your chart stays flat with no clear rise, that’s worth investigating.
Ovulation Predictor Kits
Over-the-counter ovulation predictor kits (OPKs) detect a surge in luteinizing hormone (LH) in your urine. This surge typically happens one to two days before the egg is released, giving you a short heads-up that your fertile window is open. A positive result means you should expect ovulation soon, and the next 24 to 48 hours are prime time for conception.
OPKs are widely available and straightforward to use, but they have limits. They confirm that your brain is sending the signal to ovulate, not that ovulation actually follows through. In some cases, particularly with conditions like polycystic ovary syndrome (PCOS), LH can surge without an egg being released. Pairing OPKs with mucus tracking or temperature charting gives a more complete picture.
Period Regularity as a Baseline Indicator
A regular menstrual cycle, one that arrives roughly every 21 to 35 days, is a good baseline sign that you’re ovulating. Cycles that are wildly unpredictable, frequently skipped, or absent altogether suggest something may be disrupting ovulation. Common culprits include PCOS, thyroid disorders, high stress, and being significantly underweight. A BMI of 18.5 or lower can cause your body to stop producing enough estrogen, leading to irregular or absent periods and halted ovulation.
Regularity alone doesn’t guarantee fertility, but irregularity is one of the earliest red flags that something needs attention.
Blood Tests That Measure Ovarian Reserve
If you want a deeper look at your fertility, blood tests can measure hormones that reflect how many eggs your ovaries have left, known as ovarian reserve.
The most commonly used marker is anti-Müllerian hormone (AMH). Average AMH falls between 1.0 and 3.0 ng/mL. Below 1.0 ng/mL is considered low, and below 0.4 ng/mL is severely low. AMH declines naturally with age: a typical 25-year-old might have an AMH around 3.0 ng/mL, dropping to about 1.5 ng/mL by 35 and 1.0 ng/mL by 40. A lower-than-expected AMH for your age doesn’t mean you can’t conceive, but it suggests your window may be shorter than average.
Another useful test is a day-21 progesterone blood draw (done about a week after expected ovulation). A level above 10 ng/mL confirms that ovulation occurred and your body is producing enough progesterone to support an early pregnancy. A level below that threshold may indicate you didn’t ovulate that cycle or that progesterone production was insufficient.
Ultrasound and Antral Follicle Count
A transvaginal ultrasound early in your cycle can count the small, resting follicles visible on your ovaries. This antral follicle count (AFC) is another way to estimate ovarian reserve. General ranges by age look like this:
- Early 20s to mid-30s: 12 to 30 follicles
- Ages 31 to 40: 8 to 15 follicles
- Ages 41 to 46: 4 to 10 follicles
A count on the lower end for your age group doesn’t automatically mean infertility, but combined with a low AMH, it paints a clearer picture. Fertility specialists typically look at AFC and AMH together rather than relying on one number alone.
At-Home Hormone Tests
A growing number of at-home kits now let you test fertility hormones from a finger prick or urine sample. Researchers at the University of Chicago developed a handheld device for measuring estradiol (a key fertility hormone) that showed a 96.3% correlation with standard lab equipment. Similar products are expanding to measure multiple hormones on a single test cartridge. These kits can be a useful starting point if you want data before committing to a clinic visit, though they work best as a screening tool rather than a definitive diagnosis.
Male Fertility Matters Too
About half of fertility challenges involve a male factor, so it’s worth looking at both partners. A semen analysis is the standard test. Current World Health Organization benchmarks consider these values normal:
- Total sperm count: 39 million or more per ejaculate
- Motility: at least 42% of sperm moving
- Morphology: more than 4% with normal shape
Numbers below these thresholds don’t rule out natural conception, but they lower the odds per cycle. Lifestyle factors like smoking, heavy alcohol use, heat exposure, and obesity can all drag these numbers down, and improvements in those areas often bring measurable changes within two to three months (roughly the time it takes to produce a new batch of sperm).
When to Get a Professional Evaluation
The American Society for Reproductive Medicine recommends seeking evaluation after 12 months of regular, unprotected intercourse if you’re under 35. If you’re 35 or older, that timeline shortens to 6 months. For people over 40, earlier and more immediate evaluation is reasonable. These timelines assume no obvious red flags like absent periods, known endometriosis, or a history of pelvic surgery. If any of those apply, there’s no reason to wait the full year.
A fertility evaluation typically includes the hormone blood work and ultrasound described above, plus a test to check whether your fallopian tubes are open. For male partners, a semen analysis is usually the first step. Together, these tests identify the most common barriers to conception and help determine whether you need treatment or simply more time.