Fertility isn’t a simple yes-or-no status. It exists on a spectrum, and most people can get a reasonable picture of where they stand by combining body awareness, at-home tracking, and, when needed, targeted medical tests. A woman in her early to mid-20s has roughly a 25 to 30 percent chance of conceiving in any given month, while by age 40 that drops to about 5 percent. Those numbers are population averages, though. Your individual fertility depends on ovulation, hormone levels, reproductive anatomy, and your partner’s sperm health.
Signs Your Body Gives You Each Month
Your body produces visible clues about fertility throughout your menstrual cycle, and learning to read them costs nothing. The most reliable signal is cervical mucus. In the days leading up to ovulation, discharge becomes wet, stretchy, and slippery, often described as resembling raw egg whites. This consistency exists for a reason: thin, slippery mucus makes it easier for sperm to swim through the cervix and into the uterus. If you notice this type of discharge regularly, it’s a strong sign that your body is gearing up to ovulate.
Earlier in the cycle, mucus tends to be sticky or pasty, and there may be very little of it. As estrogen rises closer to ovulation, the texture shifts. Tracking this pattern over two or three cycles can help you identify your fertile window, which typically spans the five days before ovulation plus ovulation day itself.
Basal body temperature offers another data point, though it works differently. After ovulation, your resting temperature rises slightly, usually less than half a degree Fahrenheit. You won’t catch this shift with a normal thermometer reading during the day. It requires taking your temperature first thing in the morning, before getting out of bed, using a thermometer sensitive to tenths of a degree. The catch is that the temperature rise confirms ovulation only after it’s already happened. Over several months of charting, though, you can see whether you’re ovulating consistently and roughly when it occurs.
Regular menstrual cycles between 21 and 35 days are a good general indicator that ovulation is happening. Cycles that vary wildly in length, or stretches of three to four months without a period, suggest ovulation may not be occurring reliably.
At-Home Ovulation Tests
Ovulation predictor kits, available at most pharmacies, detect a surge in luteinizing hormone (LH) in your urine. This hormone spikes about 24 to 36 hours before ovulation. A positive result, usually shown as a smiley face or a dark test line, means ovulation is likely within the next day and a half. These kits are useful because they give you a heads-up before ovulation rather than confirming it after the fact.
For best results, test in the early afternoon and try not to drink large amounts of fluid for a couple of hours beforehand, since diluted urine can weaken the reading. Start testing a few days before you expect to ovulate. If your cycles are irregular, you may need to test over a longer window, which can get expensive.
What Irregular Cycles Can Tell You
Irregular periods don’t automatically mean infertility, but they’re worth paying attention to. Ovulation problems account for about 25 percent of infertility cases in couples who struggle to conceive. Several conditions can disrupt the regular release of eggs.
Polycystic ovary syndrome (PCOS) is the most common culprit, interfering with how eggs develop and release from the ovaries. Thyroid disorders, both overactive and underactive, can throw off your cycle. A condition called hyperprolactinemia, where the body produces too much of the hormone prolactin, also disrupts ovulation. Less commonly, primary ovarian insufficiency causes the ovaries to lose normal function before age 40, leading to irregular or infrequent periods that can persist for years. Excessive exercise, eating disorders, and extreme stress can suppress ovulation too.
If your periods are consistently irregular, a blood test can check hormone levels and help identify any underlying cause. Many of these conditions are treatable, and restoring regular ovulation often restores fertility.
Medical Tests That Measure Fertility
When home tracking isn’t enough, or you’ve been trying to conceive without success, several medical tests can give you a clearer picture.
AMH Blood Test
Anti-Müllerian hormone (AMH) is produced by cells in the ovarian follicles, and its level in your blood reflects your ovarian reserve, essentially how many eggs you have left. Average AMH falls between 1.0 and 3.0 ng/mL. Below 1.0 is considered low, and 0.4 or below is severely low. These numbers shift naturally with age. At 25, a typical lower-end value is about 3.0. By 35, it drops to around 1.5, and by 40, it’s roughly 1.0. AMH can be tested on any day of your cycle, which makes it convenient. Keep in mind it estimates egg quantity, not egg quality, so it’s one piece of the puzzle rather than a complete answer.
HSG (Tubal Patency Test)
A hysterosalpingogram checks whether your fallopian tubes are open and whether the uterus has a normal size and shape. During the test, a contrast dye is placed into the uterus through the cervix while X-ray images are taken. The dye outlines the inner structures and shows whether it flows freely through each tube. Blocked or partially blocked tubes can prevent sperm from reaching the egg or stop a fertilized egg from traveling to the uterus. The procedure takes about 10 to 15 minutes and can cause mild cramping similar to period pain.
Hormone Panel
Beyond AMH, doctors may check follicle-stimulating hormone (FSH), estradiol, thyroid hormones, and prolactin levels. Together, these reveal whether the hormonal signals that drive ovulation are functioning normally. FSH is typically drawn on day 2 or 3 of your cycle for the most accurate reading.
Male Fertility Matters Equally
About half of fertility problems involve a male factor, so it’s important for both partners to be evaluated. A semen analysis is the standard first step. The World Health Organization’s reference values call for at least 39 million sperm per ejaculate, with 42 percent or more showing motility (the ability to move). At least 30 percent should be swimming forward progressively, and more than 4 percent should have normal shape. Falling below these thresholds doesn’t mean conception is impossible, but it can reduce the odds significantly.
A semen analysis is simple, requiring only a sample collected after two to five days of abstinence. Results can vary from one sample to the next, so an abnormal result is usually repeated before drawing conclusions.
How Weight Affects Fertility
Body weight plays a measurable role for both men and women. Women with a BMI over 30 have lower fertility rates, and the effect compounds when both partners carry excess weight. Couples where both members have a BMI over 35 experience about 60 percent lower fertility compared to couples where both are under 25. Excess body fat can disrupt hormone balance, interfere with ovulation, and reduce sperm quality. On the other end, being significantly underweight can suppress ovulation entirely. Reaching a BMI in the normal range is one of the most impactful lifestyle changes for improving fertility.
When to Get a Formal Evaluation
The American College of Obstetricians and Gynecologists recommends a fertility evaluation if you’ve been trying to conceive for 12 months without success and you’re under 35. If you’re over 35, that timeline shortens to 6 months. If you’re over 40, seek an evaluation right away rather than waiting. These timelines exist because age-related fertility decline accelerates in the late 30s, and earlier intervention gives you more options.
Regardless of age, it’s reasonable to seek testing sooner if you have known risk factors: very irregular or absent periods, a history of pelvic infections, endometriosis, prior cancer treatment, or a partner with a known reproductive issue. Getting answers early gives you time to act on them.