Infertility is defined as the inability to conceive after 12 months of regular, unprotected sexual intercourse (or after 6 months if the female partner is over 35 years old). It is not a disease, but a symptom of an underlying issue in the reproductive system of one or both partners that prevents pregnancy from occurring.
Infertility can be due to problems with ovulation (egg release), the fallopian tubes, the uterus, or the cervix in the female partner – or with sperm production, sperm delivery, or hormonal issues in the male partner. It can be a temporary or permanent condition, and in many cases, it is treatable.
Crucially, infertility is a couple’s issue. It affects both partners emotionally and physically, and it should always be investigated together.
How Common Is It?
Infertility affects approximately 1 in 7 couples in the UK. For every 100 couples trying to conceive, 80–90 will conceive naturally within 1 year and 95 will conceive within 2 years. Fertility naturally declines with age, particularly after 35 in women and after 40–45 in men, where sperm quality gradually declines.
Causes
Infertility can be caused by female factors, male factors, or a combination of both. In about a quarter of all cases, no specific cause is found in either partner – this is called unexplained infertility.
Overall Breakdown
- Male factors – about 30% of cases
- Female factors – about 30% of cases
- Combined (both partners) – about 20–30%
- Unexplained – about 10–20%
Female Factors
Ovulation Disorders (Around 25% of Female Cases)
- Polyendocrine Metabolic Ovarian Syndrome (PMOS) – a hormone imbalance that prevents regular ovulation.
- Hypothalamic dysfunction – often linked to very high or very low body weight, excessive exercise, or severe stress.
- Premature Ovarian Insufficiency (POI) – when the ovaries stop working normally before age 40.
- Hyperprolactinaemia – high levels of the hormone prolactin, which can stop ovulation.
Tubal Damage or Blockage
- Pelvic Inflammatory Disease (PID) – often caused by chlamydia or gonorrhoea.
- Previous ectopic pregnancy – surgery to remove a tubal pregnancy can damage the tube.
- Endometriosis – can cause adhesions that block the tubes.
- Previous sterilisation (tubal ligation) or failed reversal.
Uterine or Cervical Factors
- Fibroids – particularly submucosal fibroids that distort the uterine cavity.
- Polyps – benign growths in the uterine lining.
- Asherman’s syndrome – scar tissue inside the uterus.
- Cervical stenosis – a narrowed cervix that can impede sperm passage.
Endometriosis
- Endometrial tissue growing outside the uterus can cause inflammation, scarring, and distortion of pelvic organs, affecting egg release, tube function, and implantation.
Age-Related Decline
- Women are born with all the eggs they will ever have. As you age, both the quantity and quality of your eggs decline, making conception harder and miscarriage more likely.
Male Factors
Sperm Disorders (Most Common Male Cause – Around 90% of Male Cases)
- Low sperm count (oligospermia) – fewer than 15 million sperm per millilitre.
- Absent sperm (azoospermia) – no sperm in the ejaculate.
- Poor sperm motility (asthenospermia) – sperm that do not swim well enough to reach the egg.
- Abnormal sperm shape (teratospermia) – sperm with structural defects that prevent fertilisation.
- High levels of DNA fragmentation – damaged genetic material in sperm, making fertilisation less likely.
Structural or Obstructive Issues
- Varicocele – a swelling of the veins in the scrotum.
- Blockages in the vas deferens or ejaculatory ducts.
- Previous vasectomy or failed reversal.
Hormonal Disorders
- Hypogonadism – low testosterone production.
- Hyperprolactinaemia – high prolactin levels.
- Thyroid disorders – both overactive and underactive thyroid can affect sperm.
Genetic Conditions
- Klinefelter syndrome (XXY chromosomes).
- Y-chromosome microdeletions.
- Cystic fibrosis gene mutations.
Lifestyle and Environmental Factors
- Smoking – damages sperm DNA and reduces count and motility.
- Excessive alcohol – lowers testosterone and reduces sperm quality.
- Illicit drugs – including cannabis, anabolic steroids, and cocaine.
- Overheating the testicles.
- Obesity – causes hormonal imbalances.
- Occupational exposures to pesticides, heavy metals, radiation, or industrial chemicals.
Erectile or Ejaculatory Dysfunction
- Retrograde ejaculation – semen passes backwards into the bladder.
- Erectile dysfunction – inability to maintain an erection.
- Spinal cord injury or neurological conditions.
Symptoms
In Women
- Irregular menstrual cycles.
- Painful or heavy periods.
- Pain during intercourse (dyspareunia).
- Persistent pelvic pain.
- Milk discharge from the breasts not related to pregnancy or breastfeeding.
In Men
- Changes in sexual function.
- Pain, swelling, or a lump in the testicles.
- A small, firm testicle.
- Reduced facial or body hair.
- A history of testicular injury, undescended testes, or mumps in adulthood.
Diagnosis
Tests for the Female Partner
- Medical history and physical examination.
- Ovulation testing.
- Hormone blood tests including FSH, LH, Oestradiol, AMH and TFT.
- Transvaginal ultrasound scan.
- HyCoSy.
- Hysteroscopy.
- Laparoscopy.
Tests for the Male Partner
- Medical history and physical examination.
- Semen analysis.
- Hormone blood tests.
- Scrotal ultrasound.
- Genetic testing.
- Post-ejaculatory urine analysis.
Treatment Options
Lifestyle Modifications (For Both Partners)
- Achieving a healthy BMI (19–25).
- Stopping smoking.
- Reducing alcohol and caffeine intake.
- Moderating intense exercise.
- For men: wearing looser underwear and avoiding excessive scrotal heat.
Medical Treatments
- Clomifene citrate (Clomid).
- Letrozole.
- Gonadotropins (FSH/LH injections).
- Human Chorionic Gonadotropin (hCG) or FSH injections.
Surgical Treatments
- Laparoscopic surgery.
- Hysteroscopic surgery.
- Tubal surgery.
- Varicocelectomy.
- Vasectomy reversal.
- Surgical sperm retrieval (TESE/PESA).
Assisted Conception (ART)
- Intrauterine Insemination (IUI).
- In Vitro Fertilisation (IVF).
- ICSI (Intracytoplasmic Sperm Injection).
Third-Party Reproduction
- Donor eggs.
- Donor sperm.
- Surrogacy.
- Embryo donation.
eGynaecologist Advice (For Couples)
- Do not wait if the female partner is over 35 – if you have been trying for 6 months without success, see your gynaecologist sooner. Time is your most valuable asset.
- Infertility is a couple's issue, and both partners should be investigated from the start. A semen analysis for man is just as important as a hormone blood test for a woman.
- You should stop smoking as this ages the female partner's ovaries by up to 10 years and halves IVF success. In men, it damages sperm DNA and lowers motility.
Frequently Asked Questions
If we have unexplained infertility, is there no hope?
“Unexplained” simply means our current tests have not identified a specific cause. Many couples with unexplained infertility still conceive – either naturally or with treatments like IUI or IVF.
Does the female partner's age really matter that much?
Yes. Fertility peaks in the early 20s and begins to decline more noticeably after 35. By 40, the chance of natural conception per cycle is around 5%. Egg quality, not just quantity, declines with age
Can stress cause infertility?
Extreme physical or psychological stress can disrupt ovulation in women. In men, stress can lower libido and affect sperm quality. However, everyday stress is rarely the sole cause of infertility.
Should both partners be tested?
Absolutely. Infertility affects both partners equally. About one-third of cases are due to female factors, one-third to male factors, and one-third to a combination or are unexplained.
Can I still have a baby if my fallopian tubes are blocked?
Yes – IVF bypasses the fallopian tubes entirely, as eggs are collected directly from the ovaries and embryos are transferred straight into the uterus
Does the male partner's age matter?
Yes, but less dramatically. Male fertility declines gradually from about age 40–45, with reduced sperm quality and higher DNA fragmentation. However, men can remain fertile into their 60s and beyond.
