What Causes Infertility? A Fertility Specialist on the Most Common Reasons
Many couples expect to conceive quickly once they decide to start trying for a baby. When pregnancy test after pregnancy test comes back without the two lines they're hoping for, worry often sets in. A few months of trying doesn't necessarily mean there's a fertility problem, though. If it's taking longer than expected to conceive, or if concerning symptoms show up along the way, it's worth looking into the possible causes of infertility in both women and men. We asked dr n. med. Joanna Figuła, Deputy Medical Director at ARTVIMED Clinic in Kraków, about the most common causes of infertility and the signs that call for a consultation.
When should you start fertility testing?
Fertility testing usually begins after 12 months of regular, unprotected intercourse if the woman is under 35, or after 6 months if she's 35 or older. It's worth seeking help sooner if she's over 40, has irregular cycles, or if there's a suspicion of endometriosis, tubal disease, or a male factor. Testing should cover both partners at the same time.
Low ovarian reserve and AMH testing
Age is one of the most important factors affecting fertility in women. Over time, the number of egg cells declines and their quality drops, which lowers the chances of conceiving. When there's a clinical indication, a doctor may recommend testing AMH levels and counting antral follicles on ultrasound. These results help estimate ovarian reserve and predict how the ovaries will respond to stimulation, but on their own they don't determine whether a woman can conceive naturally. A low AMH level doesn't mean pregnancy is impossible; it needs to be read together with age, medical history, and ultrasound findings. Every woman is born with a fixed pool of ovarian follicles, and that number decreases throughout life, which is why ovarian reserve declines with age.
Hormonal imbalances and ovulation disorders
The length and regularity of your periods are worth paying attention to as well. A normal menstrual cycle usually runs 21 to 35 days. A cycle that's notably shorter or longer, significant irregularity, or spotting between periods can signal a problem. These symptoms may point to hormonal imbalances, ovulation disorders, or abnormal growth of the uterine lining. Possible causes include thyroid conditions, polycystic ovary syndrome (PMOS), luteal phase defects, obesity and related metabolic conditions, and certain medications. It's worth discussing any symptoms with a doctor, who can recommend the right tests.
Endometriosis and infertility
Severe pain during your period or during sex, chronic pelvic pain, and trouble conceiving can point to endometriosis or inflammation in the pelvis. Endometriosis is a chronic inflammatory condition in which tissue similar to the uterine lining grows outside the uterus. It affects around 10% of women of reproductive age, and diagnosis is often delayed. The inflammation and anatomical changes it causes can interfere with ovulation, fertilization, or embryo implantation, which makes endometriosis one of the more significant causes of infertility in women.
Blocked fallopian tubes after surgery or illness
Certain conditions and medical procedures can lower fertility. Abdominal surgery, pelvic inflammatory disease, or endometriosis can lead to scarring and blocked fallopian tubes, making it harder for the egg and sperm to meet. Tubal patency is assessed with a test chosen by the doctor, such as an HSG or a contrast ultrasound. Laparoscopy isn't a routine test and is only performed when there's a specific indication. For serious issues, such as blockage in both tubes, a doctor may discuss IVF with the couple. In men, fertility can be affected by things like a past case of orchitis, cancer treatment, or surgery involving the urogenital system.
Body weight, lifestyle, and fertility
Body weight and lifestyle can affect fertility in both women and men. Both excess weight and being underweight can lower the chances of conceiving, and an unhealthy body weight often comes with hormonal or metabolic imbalances. BMI is a simple screening measure based on the ratio of weight to height, but it's no substitute for an individual health assessment. Physical inactivity, smoking, heavy alcohol use, other substances, and chronic stress can also work against fertility. While you're trying to conceive, and ideally a few months before, it's worth prioritizing sleep, movement, a balanced diet, and cutting back on substances.
Causes of male infertility
A male factor is present in roughly half of couples dealing with infertility, either on its own or alongside a cause on the woman's side. Sperm count, motility, and shape can all be abnormal, as can ejaculate volume. Causes include obesity, systemic illness, smoking, exposure to toxic substances, a past case of orchitis, and radiation or chemotherapy. The basic test is semen analysis, which evaluates its key parameters. That result alone, though, isn't enough to definitively call a man fertile or infertile. If the result is abnormal, a doctor may recommend repeating the test and seeing an andrologist. Depending on the cause, treatment or assisted reproduction methods can help a couple conceive.
Is "hostile cervical mucus" really a cause of infertility?
Cervical and immune factors are rarely the sole or main cause of infertility. The term "hostile mucus syndrome" still comes up in everyday conversation, but the post-coital test isn't routinely recommended anymore. It's a subjective test with limited reproducibility, and it usually doesn't change how a case is managed. The doctor decides on the scope of testing based on the medical history and other results.
What does fertility testing actually involve?
The main goal is identifying why a couple is having trouble conceiving, looking at both partners. Fertility tests are chosen individually. For women, this usually includes a medical history, an assessment of the cycle and ovulation, and an ultrasound of the reproductive organs. Depending on what's indicated, a doctor may also order hormone tests, an assessment of ovarian reserve through AMH and antral follicle count, and a test of tubal patency. For men, semen analysis is the starting point. Based on these results, the doctor decides whether further testing, more time trying naturally, treatment, or assisted reproduction methods are needed.
