Infertility — Symptoms, Causes & Treatment | MyMedicPlus

Infertility is defined as the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse in women under 35 (6 months in women 35 and older). It affects approximately 1 in 6 couples globally — representing roughly 48 million couples. Male and female factors each contribute equally to approximately 40–50% of cases, with unexplained infertility (all investigations normal) accounting for the remaining 10–20%. Infertility is highly treatable — with access to modern assisted reproductive technologies, approximately 50–70% of couples eventually achieve parenthood. Infertility is defined as failure to achieve pregnancy after 12 months of regular unprotected intercourse (6 months if the woman is over 35). It affects approximately 1 in 6 couples worldwide — an estimated 48 million couples globally. Causes are attributable to the female partner in about 40% of cases, the male partner in 40%, combined factors in 10-15%, and unexplained in the remaining 15%. A thorough systematic evaluation of both partners is essential before initiating treatment.

Female causes: ovulatory disorders (PCOS — most common; hypothalamic dysfunction; premature ovarian insufficiency), tubal damage from pelvic inflammatory disease or endometriosis, uterine abnormalities (fibroids, polyps, Asherman's syndrome), and cervical factors. Male causes: abnormal semen parameters — oligospermia (low count), asthenospermia (poor motility), teratospermia (abnormal morphology); azoospermia from obstruction or testicular failure; varicocele; hormonal disorders. Risk factors include advanced age (female fertility declines sharply after 35), smoking, obesity, STIs causing tubal damage, endometriosis, and prior gonadotoxic chemotherapy or radiation. Ovarian reserve declines significantly from age 37, accelerating after 40, making advanced maternal age (AMA) one of the most important causes of infertility — egg quality impairs with age, not just quantity. Male factor infertility accounts for about 40% of all cases and requires semen analysis as the first investigation. Environmental factors including endocrine-disrupting chemicals, high heat exposure to testes, and anabolic steroid use are increasingly recognised causes.

Infertility itself is not symptomatic — the presenting feature is failure to conceive. However, underlying causes may have associated features: irregular or absent periods (anovulatory disorders such as PCOS or premature ovarian insufficiency), painful periods and intercourse (endometriosis), pelvic pain (PID sequelae), and galactorrhea (hyperprolactinemia). In men, underlying cause symptoms may include testicular pain or swelling (varicocele), sexual dysfunction, reduced facial or body hair (hypogonadism), or a history of cryptorchidism (undescended testes). Most couples present with no symptoms other than the inability to conceive. Irregular or absent menstrual cycles (oligomenorrhoea or amenorrhoea) are the most clinically informative symptom in female infertility — pointing to anovulation from PCOS, hypothalamic amenorrhoea, or premature ovarian insufficiency. Dysmenorrhoea and dyspareunia may indicate endometriosis. Galactorrhoea suggests hyperprolactinaemia. Male infertility is typically asymptomatic — semen analysis is the only reliable screening tool.

Female investigations: ovarian reserve assessment (antral follicle count on transvaginal ultrasound, AMH, day 3 FSH), mid-luteal phase progesterone (confirms ovulation), hysterosalpingography (HSG) for tubal patency, and thyroid function and prolactin. Male investigations: semen analysis — the cornerstone test assessing volume, count (above 16 million/mL), progressive motility (above 30%), and morphology (above 4% normal forms per WHO 2010 criteria). Abnormal semen analysis is repeated after 6–8 weeks. Hormone profile (FSH, LH, testosterone, prolactin) in azoospermia. Testicular biopsy distinguishes obstructive from non-obstructive azoospermia. Baseline investigations in couples: semen analysis (volume, concentration, motility, morphology — WHO 2021 reference values); day 2-5 FSH, LH, and oestradiol (ovarian reserve marker — elevated FSH above 10 IU/L suggests diminished reserve); AMH (anti-Mullerian hormone — best single marker of ovarian reserve — below 1.0 ng/mL indicates low reserve); transvaginal ultrasound for antral follicle count, uterine morphology, and ovarian pathology; tubal patency assessment by hysterosalpingography (HSG) or HyCoSy.

Ovulation induction with clomifene citrate or letrozole treats anovulatory infertility (especially PCOS) with cycle monitoring. Intrauterine insemination (IUI) with washed sperm is used for unexplained infertility, mild male factor, or cervical factor. In vitro fertilization (IVF) — retrieval and laboratory fertilization of eggs followed by embryo transfer — is the most effective treatment for most infertility causes. Intracytoplasmic sperm injection (ICSI) is used for severe male factor or failed conventional IVF fertilization. Surgical sperm retrieval (TESE, PESA) obtains sperm for ICSI in azoospermic men. Preimplantation genetic testing (PGT) screens embryos for chromosomal abnormalities before transfer. IVF (in vitro fertilisation) — the most effective treatment for most infertility causes — involves controlled ovarian stimulation with FSH injections, egg retrieval under sedation, fertilisation in the laboratory, and embryo transfer. Live birth rate per cycle is approximately 25-35% under age 35, declining to under 5% over age 43 using own eggs. Intracytoplasmic sperm injection (ICSI) is used for severe male factor infertility. Preimplantation genetic testing (PGT-A) screens embryos for chromosomal abnormalities before transfer.

Seek a fertility assessment from a GP after: 12 months of unprotected sexual intercourse without conception in women under 35; 6 months in women aged 35 or over; or immediately if there are known risk factors for infertility (irregular or absent periods, previous pelvic inflammatory disease, PCOS, endometriosis, previous chemotherapy or radiotherapy, undescended testes, prior ectopic pregnancy, or known genetic conditions). Do not wait longer than these timescales — female fertility declines with age, particularly after 35, and earlier assessment provides more treatment options. Both partners should be assessed simultaneously — male factor investigation (semen analysis) should begin at the same time as female investigation, as male factor contributes to 40-50% of cases. Seek urgent assessment for: signs of hyperstimulation in women on ovulation induction therapy (severe abdominal bloating, rapid weight gain, breathlessness — ovarian hyperstimulation syndrome or OHSS — a rare but serious complication requiring early medical review). All couples with infertility should be referred to a specialist fertility clinic if investigations reveal abnormalities or if conception has not occurred after appropriate investigation.

Infertility profoundly impacts psychological wellbeing — depression affects approximately 40-50% of women and 15-20% of men undergoing fertility treatment, with grief, shame, and identity disruption common. Relationship strain from invasive investigations, treatment cycles, financial burden, and repeated loss (failed IVF cycles, miscarriage) affects couple dynamics significantly. Physical complications of fertility treatments include ovarian hyperstimulation syndrome (OHSS) — a potentially serious complication of gonadotrophin stimulation causing abdominal distension, nausea, ascites, and rarely thromboembolism — occurring in 3-6% of IVF cycles with severe OHSS in 0.2-0.5%. Multiple pregnancy (twins, triplets) from multi-embryo transfer carries risks of premature birth, low birth weight, cerebral palsy, and neonatal intensive care admission for offspring. Repeat IVF failures and surgical interventions for tubal or uterine factors carry cumulative surgical risks. Unexplained infertility with delayed conception is associated with increased risk of adverse obstetric outcomes in eventual pregnancies. Infertility associated with polycystic ovary syndrome (PCOS) carries metabolic risks including type 2 diabetes, cardiovascular disease, and endometrial cancer from unopposed oestrogen in anovulatory women.

Preserve reproductive health: avoid and treat STIs promptly (tubal damage is a major preventable cause of female infertility); quit smoking (damages both eggs and sperm quality); achieve healthy weight (BMI 18.5–30); limit alcohol; manage chronic conditions such as diabetes, thyroid disease, and PCOS. Egg freezing before age 35 or before gonadotoxic cancer treatment preserves future fertility options. Seek fertility assessment if not pregnant after 12 months (6 months if above 35, or sooner with known risk factors such as irregular cycles, previous PID, or male reproductive history issues).