Infertility in women is officially defined by one key timeline: not getting pregnant after 12 months of regular, unprotected sex if you’re under 35, or after 6 months if you’re 35 or older. About 13.4% of women ages 15 to 49 have impaired fertility, so it’s far more common than most people realize. While the only definitive way to know is through medical evaluation, several signs can point to a problem before you ever see a doctor.
The Clearest Early Sign: Your Period Pattern
Your menstrual cycle is the most visible window into your fertility. Cycles that are consistently shorter than 21 days or longer than 35 days suggest you may not be ovulating regularly. Going months without a period, as some women do, is an even stronger signal. Ovulation problems account for about 25% of infertility cases among couples struggling to conceive.
That said, irregular periods don’t automatically mean infertility. Some women with unpredictable cycles still ovulate, just less frequently. The reverse is also true: you can have clockwork periods and still face fertility issues from other causes, like blocked fallopian tubes or uterine problems. But if your periods are absent, wildly irregular, or have changed dramatically in flow or timing, that’s worth investigating.
Painful Periods and Pelvic Pain
Period pain that disrupts your daily life, especially pain that worsens over time, can be a sign of endometriosis. This condition occurs when tissue similar to the uterine lining grows outside the uterus, causing chronic inflammation and pelvic pain that can reduce fertility. Pain during sex, particularly deep pain, is another hallmark. Endometriosis is notoriously underdiagnosed, with many women waiting years before getting answers.
Pelvic pain outside your period can also point to pelvic inflammatory disease (PID), an infection of the reproductive organs usually caused by sexually transmitted infections. PID creates scar tissue in the fallopian tubes, which can block eggs from reaching the uterus. The more episodes of PID you’ve had, the greater your risk of permanent tubal damage. Even a single untreated infection can cause enough scarring to affect fertility.
Hormonal Red Flags You Can See
Polycystic ovary syndrome (PCOS) is one of the most common causes of female infertility, and it often announces itself through visible symptoms. Excess hair growth on the face, chest, or back, persistent acne, thinning hair on the scalp, and weight gain concentrated around the midsection are all driven by elevated levels of male hormones. PCOS disrupts ovulation, meaning your ovaries may not release an egg each month.
Other hormonal signs to watch for include sudden changes in skin (severe dryness or oiliness), unexplained weight changes, or milky nipple discharge when you’re not pregnant or breastfeeding. These can signal thyroid disorders or elevated prolactin levels, both of which interfere with ovulation.
Weight and Lifestyle Factors
Body weight has a measurable impact on fertility. Women with a BMI of 32 or higher at age 18 have nearly three times the risk of infertility caused by absent ovulation compared to women at a healthy weight. Even among women who do ovulate, the chance of conceiving on their own drops by about 5% for every one-point increase in BMI.
Being significantly underweight matters too. Excessive exercise, eating disorders, and very low body fat can shut down ovulation entirely. Your body interprets extreme energy deficits as a signal that it’s not safe to support a pregnancy, and your cycles may stop or become sporadic.
Your Medical History Matters
Certain events in your past raise the likelihood of fertility problems, even if you feel fine now:
- Previous STIs or pelvic infections: Chlamydia and gonorrhea can silently scar the fallopian tubes. Many women never know they had an infection until they try to conceive.
- Prior ectopic pregnancy: A pregnancy that implanted in a fallopian tube often indicates existing tube damage and raises the risk of future blockages.
- Abdominal or pelvic surgery: Operations on the ovaries, uterus, or appendix can create adhesions (bands of scar tissue) that interfere with egg transport or implantation.
- Cancer treatment: Chemotherapy and radiation, particularly to the pelvic area, can damage eggs and reduce ovarian reserve.
When You’ve Had a Baby Before
Having a previous pregnancy doesn’t guarantee you can get pregnant again. Secondary infertility, the inability to conceive or carry a pregnancy after previously giving birth, affects about 11% of couples in the United States. It’s just as common as primary infertility.
The same timelines apply: if you’re under 35 and haven’t conceived after a year of trying, or over 35 and it’s been six months, something may have changed. Age, new hormonal conditions, weight shifts, or infections acquired since your last pregnancy can all play a role. The causes and treatments overlap almost entirely with primary infertility.
What Happens During a Fertility Evaluation
If the signs above sound familiar, or if you’ve been trying without success within the timelines described, a fertility evaluation can identify the specific problem. For women over 40, the American Society for Reproductive Medicine recommends more immediate evaluation rather than waiting the full six months.
Blood tests check key hormones that reflect your egg supply and ovulation status. One hormone, anti-Müllerian hormone (AMH), gives a snapshot of your remaining egg reserve. Low AMH levels suggest diminished ovarian reserve. Another hormone, FSH, tends to rise when the ovaries are working harder to stimulate egg development, which can indicate declining fertility.
A progesterone blood test taken about a week after expected ovulation confirms whether you actually released an egg that cycle. This is one of the simplest and most informative tests in a fertility workup.
Checking for Structural Problems
A hysterosalpingogram (HSG) is an X-ray procedure that checks whether your fallopian tubes are open and whether your uterus has a normal shape. During the test, dye is injected through the cervix. If the dye flows freely through both tubes and spills out the ends, the tubes are clear. If the dye hits a barrier, it reveals a blockage.
The HSG can also detect uterine abnormalities like fibroids, polyps, a divided uterus (septate uterus), or adhesions inside the uterine cavity. Some of these structural issues cause no symptoms at all but can prevent an embryo from implanting or a pregnancy from continuing.
Signs That Don’t Mean What You Think
Some things women worry about are less predictive of infertility than they assume. Spotting between periods, for instance, can indicate a hormonal imbalance but doesn’t necessarily mean you can’t conceive. Similarly, a family history of early menopause raises your risk of diminished ovarian reserve, but it’s not a certainty. And using hormonal birth control for years does not reduce your fertility after stopping, despite a persistent myth. Ovulation typically returns within one to three months after discontinuing most contraceptives.
The bottom line is that some causes of infertility produce obvious warning signs, while others are completely silent. Women with blocked tubes, mild endometriosis, or diminished egg reserve often feel perfectly healthy. The timeline of trying to conceive remains the most reliable trigger for seeking evaluation, but paying attention to your cycle, your body’s hormonal signals, and your medical history can help you identify potential problems earlier.