What Causes Infertility? Female, Male and Couple Factors

• Infertility is defined as no conception after 12 months of regular unprotected sex (6 months if the woman is 35 or older) and is not always anyone's 'fault'.
• Causes split roughly into thirds: female factors, male factors, and combined or unexplained factors. A male partner is involved in close to half of all cases.
• The most common female cause in India is an ovulation problem, usually PCOS; the most common treatable male cause is varicocele.
• Female age is the single biggest factor and cannot be reversed by lifestyle, so do not delay evaluation once you suspect a problem.
• Both partners should be evaluated together from the start, ideally including a semen analysis before any extensive testing of the woman.

Infertility has a precise clinical definition: 12 months of regular, unprotected intercourse without conception when the female partner is under 35, or 6 months when she is 35 or older. These numbers are not arbitrary. They reflect how long fertile couples normally take to conceive. Among couples with no fertility problem, about 25 percent conceive in the first month, 60 percent within six months, 80 percent within a year, and 90 percent within 18 months. Couples who have not conceived after 12 months sit at the tail of that curve, where an identifiable cause becomes much more likely.

The threshold drops to six months at 35 because of how steeply female fertility declines with age. For a woman in her late 20s or early 30s, waiting a full year before testing is reasonable. For a woman in her late 30s, every extra month of unsuccessful trying is a meaningful loss of remaining fertile time and a reason to start sooner.

Some couples should not wait at all. Earlier evaluation is appropriate when there is an obvious reason to suspect a problem, including polycystic ovary syndrome with irregular periods, Understanding Endometriosis: Causes, Symptoms & Management, prior pelvic infection or surgery, previous chemotherapy or pelvic radiation, a known uterine anomaly, undescended testes or testicular surgery, mumps affecting the testes, or any sign of low testosterone. If you have already failed to conceive once, secondary infertility deserves the same workup as a first pregnancy that is not happening.

FOGSI and the Indian Society for Assisted Reproduction align with international guidance from ESHRE, ASRM and NICE on these thresholds. In Indian practice, women over 35 are often advised to have at least a basic check, including ovarian reserve testing, before or soon after they start trying, so expectations and timing can be set realistically.

Female factors account for roughly a third of infertility. They fall into a few clear buckets: ovulation problems, tubal or pelvic damage, uterine issues, and age-related decline in egg quality.

Ovulation disorders are the largest single category and, encouragingly, the most treatable. The dominant cause in India is PCOS, which affects an estimated 10 to 20 percent of Indian women of reproductive age and is the leading cause of anovulatory infertility worldwide. PCOS disrupts the hormonal signalling that triggers a monthly egg release, often alongside insulin resistance and excess androgens. The good news: with appropriate ovulation induction, most women with PCOS and no other issue can conceive. Other ovulation problems include thyroid dysfunction, high prolactin, hypothalamic causes (low body weight, very heavy exercise or major stress that switches off the cycle), and primary ovarian insufficiency. If your periods are irregular or absent, tracking ovulation and getting hormones checked is the logical first step.

Tubal and pelvic factor infertility means the fallopian tubes are blocked or damaged, so sperm and egg cannot meet. The most common cause globally is pelvic inflammatory disease, usually following untreated chlamydia or gonorrhoea, which scars the tubes. In India, genital tuberculosis is an important and often-missed cause of tubal damage, particularly in women from higher-prevalence regions. Endometriosis, where uterine-like tissue grows outside the uterus and forms adhesions, is another major contributor that is frequently diagnosed late. Tube status is checked with an HSG or, where needed, with Laparoscopy for Women in India: Procedure, Cost & Recovery.

Uterine factors include septate or bicornuate uterus, fibroids that bulge into the cavity, polyps, and Asherman syndrome (scarring inside the uterus, often after a previous D&C). These are assessed by ultrasound, saline-infusion sonography, or hysteroscopy, and many can be corrected surgically.

Egg quality declines with age as a rising share of eggs become chromosomally abnormal. This lowers conception rates and raises miscarriage risk. The decline becomes clinically meaningful from the mid-30s and is steep after 40, though diminished ovarian reserve can appear earlier and is flagged by a low AMH or antral follicle count.

Male factors account for about a third of infertility on their own and contribute in close to half of all couples. The deep-rooted assumption in many Indian families that infertility is a woman's problem is simply wrong, and it causes real harm, subjecting women to investigations and treatment while the male partner is never tested. A semen analysis is the foundation of male evaluation and should be done in every couple, ideally before any extensive female workup. For a broader reality-check on the topic, our guide to male factor infertility breaks down the hidden 40 percent.

Semen analysis reports several things measured against WHO 2021 reference values: semen volume (1.5 mL or more), sperm concentration (15 million per mL or more), total count (39 million or more), motility (40 percent total, 32 percent progressive), and normal morphology (4 percent or more by strict criteria). Reduced count is oligospermia, reduced motility is asthenospermia, abnormal shape is teratospermia, and no sperm in the ejaculate is azoospermia. Combinations are common.

Severe oligospermia and azoospermia have specific causes: hormonal (failure of the pituitary signal), primary testicular failure (Klinefelter syndrome, prior undescended testes, past chemotherapy or radiation, mumps orchitis, varicocele), and obstruction (congenital absence of the vas, prior vasectomy, or post-infection scarring). Working these up involves hormone tests (FSH, LH, testosterone), a testicular ultrasound, and sometimes genetic testing or a biopsy.

Varicocele — dilated veins around the testis — is the most common surgically correctable cause of male infertility, present in about 15 percent of all men and 40 percent of men with infertility. Repair can improve sperm parameters in selected cases. Lifestyle and environmental factors matter too: heat (tight clothing, frequent hot baths), tobacco and cannabis, anabolic steroids, certain medications, and obesity all reduce sperm quality. Because sperm take roughly 70 to 90 days to mature, any lifestyle change takes about three months to show up on a repeat test.

Delivery problems — erectile dysfunction, retrograde ejaculation, or anatomical issues — can prevent sperm reaching the egg even when production is normal. Diabetes, neurological conditions and some pelvic surgeries are common contributors, and a urologist with reproductive expertise can usually help, including retrieving sperm for assisted reproduction when natural conception is not possible.

About a third of infertility involves combined factors in both partners, or stays unexplained after a full workup. Combined infertility is common because borderline issues add up: a man with low-normal sperm parameters and a woman with mild endometriosis may together have a real problem that neither would have alone.

Unexplained infertility — no identifiable cause after standard testing — affects roughly 15 to 20 percent of couples. The label reflects the limits of current testing, not the absence of any cause. Many of these cases involve subtle egg or sperm quality issues, fertilisation problems, or implantation factors that routine tests do not detect. More advanced tests (sperm DNA fragmentation, endometrial receptivity testing) explain a few additional cases, though the clinical value of many add-ons is debated.

Management is usually stepwise: watchful waiting for younger couples with a short duration of trying; ovulation induction with timed intercourse or IUI as middle options; and IVF as the single most effective intervention. The right intensity depends on the woman's age, how long you have been trying, your preferences, and your resources. When the woman is over 38 or infertility has lasted more than three years, IVF often becomes the primary recommendation because its per-cycle success is much higher than gentler options.

Unexplained infertility carries a particular emotional weight, because the absence of a clear cause makes it hard to feel anything has been truly fixed. Counselling and peer support genuinely help, and most established Indian fertility clinics now offer or refer to mental health professionals familiar with this journey.

Female age is the most important single factor in fertility, and it is not modifiable. Fertility dips subtly in the late 20s, more noticeably in the early 30s, significantly from the mid-30s, and steeply after 40. By 35, the per-cycle chance of conceiving is roughly half what it was at 25; by 40, roughly half again. Miscarriage risk rises in parallel as more embryos carry chromosomal errors. Natural conception is uncommon by 45, though it does happen. These changes reflect declining egg quality and, more slowly, declining egg quantity.

For Indian women specifically, the rising age at marriage and first pregnancy over the last two decades is a major reason infertility is becoming more common. Many urban women now first try to conceive in their early-to-mid 30s, shifting the whole population toward ages where evaluation should not be delayed. Our calm guide to TTC after 30 covers this without panic, and our geriatric pregnancy explainer covers what 'advanced maternal age' really means.

Male age also matters, though less dramatically and more variably. Sperm parameters and genetic quality decline gradually, with measurable effects on offspring when both partners are older. Most men stay fertile into their 60s, but the decline is not zero.

The practical takeaway is simple: for older couples, earlier evaluation and treatment improve outcomes. A woman of 38 who has tried for six months should seek evaluation now, not in another six. For those anticipating delayed childbearing, egg freezing is an option; under the ART (Regulation) Act 2021, it is permitted in India for medical and personal reasons, though access is still concentrated in metro fertility centres.

Lifestyle affects fertility for both partners, sometimes enough to matter clinically. Body weight at the extremes is one of the clearest levers. Both being underweight (BMI under 18.5) and obesity (BMI over 30) reduce female fertility and worsen IVF outcomes, and obesity reduces sperm quality in men. Preconception weight optimisation is one of the first interventions in many evaluations, and even a modest 5 to 10 percent change can shift the odds.

Tobacco lowers fertility for everyone. Smoking reduces ovarian reserve and shortens reproductive lifespan in women; in men it cuts count, motility and morphology and damages sperm DNA. Heavy alcohol reduces fertility in both partners, and cannabis affects both ovulation and sperm and is best stopped. A Mediterranean-style diet rich in vegetables, whole grains, fish and healthy fats is associated with better outcomes, though the evidence is observational. Specific deficiencies, particularly vitamin D, iron and B vitamins, are common in Indian women and worth correcting. Moderate caffeine (up to 200 to 300 mg a day, about two cups of coffee) is generally considered safe.

Environmental endocrine disruptors — BPA, phthalates, some pesticides and air pollution — have been linked to reduced fertility in some studies, though the evidence is mixed. Reasonable, low-cost steps include choosing BPA-free containers, washing produce, and avoiding heating food in plastic. Air pollution in many Indian cities far exceeds WHO limits and has been associated with reduced fertility and pregnancy complications; it is hard to fix individually but is a genuine reason for systemic concern.

A word on stress. It is the most over-blamed factor and the evidence for a direct effect is weaker than the cultural narrative claims. Severe sustained stress probably has some impact, but 'just relax and you'll get pregnant' is unsupported and unkind. Stress management is worth doing for your wellbeing during treatment — it should never replace proper medical evaluation.

• Both partners evaluated together, with a semen analysis done early
• Female workup: cycle and ovulation assessment, hormones (including thyroid and prolactin), ovarian reserve (AMH, antral follicle count), and tubal patency by HSG
• Male workup: semen analysis, repeated if abnormal, with hormones and ultrasound if indicated
• Imaging of the uterus and pelvis by ultrasound, with hysteroscopy or laparoscopy if needed
• Early referral when the woman is 35 or older, periods are irregular, or there is a known risk factor

• You have tried to conceive for 12 months (or 6 months if the woman is 35 or older) without success.
• The woman's periods are irregular, very infrequent, or absent, which suggests an ovulation problem worth checking now.
• There is a known risk factor: PCOS, endometriosis, prior pelvic infection or surgery, genital tuberculosis, past chemotherapy or radiation, undescended testes, or a known uterine anomaly.
• There is a history of two or more miscarriages, which warrants a recurrent-loss workup rather than simply trying again.
• The male partner has a known issue: prior testicular surgery, mumps affecting the testes, a visible varicocele, erectile or ejaculatory difficulty, or a previous abnormal semen test.
• The woman is 38 or older, in which case do not delay even a few months — start evaluation as soon as you suspect a problem.

• WHO — Infertility: Key facts
• WHO laboratory manual for the examination and processing of human semen (6th edition)
• NICE — Fertility problems: assessment and treatment (CG156)
• ACOG — Evaluating Infertility (FAQ)
• ESHRE — Guidelines on Unexplained Infertility
• ICMR — National Guidelines for Accreditation, Supervision and Regulation of ART Clinics in India