Infertility
By The Treatment Registry editors
Infertility is generally defined as inability to conceive after 12 months of regular unprotected intercourse (6 months over age 35). Causes are female-factor, male-factor, both, or unexplained. Treatment is staged from lifestyle and medical optimisation through assisted reproductive technology, with specific approaches tailored to the underlying cause.
Clinical overview
Signs and symptoms
Infertility presents as the inability to become pregnant after at least one year of regular, unprotected sexual intercourse involving a male and female partner, or after six months where the woman is over 35, has a history of endometriosis, has infrequent or irregular menses, or where a male factor is involved. It is defined by this reproductive failure rather than by symptoms of its own. The most common female-factor causes are hormonal and usually manifest as scanty or absent menstrual periods, and ovarian reserve declines with age; male-factor infertility is most commonly due to deficiencies in the semen.
Causes and risk factors
Male infertility is responsible for 20-30% of cases, female infertility for 20-35%, and combined problems in both partners for 25-40%; in 10-20% of cases no cause is found. The most common cause of female infertility is disordered ovulation, of which about 70% is due to polycystic ovarian syndrome, with other hormonal contributors including low oestrogen, imbalanced GnRH secretion and ageing, which reduces ovarian reserve; some women experience primary ovarian insufficiency before age 40. Tubal infertility accounts for 11-67% of female infertility and endometriosis for 25-40%. Male infertility is most commonly due to deficiencies in the semen. Additional recognised causes include iodine deficiency, delayed puberty and antisperm antibodies, which have been implicated in around 10-30% of infertile couples.
How it is diagnosed
A doctor or women's health nurse practitioner takes a medical history and performs a physical examination of both partners, and can carry out basic tests to identify a reason for the failure to conceive. Blood tests are common and may include serologies for infections such as hepatitis B, hepatitis C, HIV, syphilis and rubella, with optional tests such as karyotypes. In women, specific tests may measure anti-Mullerian hormone to assess ovarian reserve, thyroid-stimulating hormone, prolactin and vitamin D. Semen quality is used as a surrogate measure of male fecundity. Where necessary, patients are referred to a fertility clinic for more specialised tests, and the results help determine the most appropriate treatment.
Who it affects
Prevalence varies with the definition used. The World Health Organization reported in 2023 that about 17.5% of people experience infertility during their lifetime, with a point prevalence of 12.6%, and rates have risen by about 4% since the 1980s, largely owing to increasing age. In the UK fertility problems affect about one in seven couples; roughly 84% who have regular unprotected intercourse conceive within a year and about 95% within two years. About 94% of women aged 35 conceive after three years of trying, compared with about 77% of women aged 38.
Clinical overview sourced from encyclopaedic medical reference; see sources below. General information only — not a substitute for individual clinical assessment.
Treatment ladder
Conservative options are first-line where appropriate; surgical options are typically reserved for cases where lower-tier options are unsuitable or have failed. Decisions are individual and depend on clinical assessment.
Conservative
- Lifestyle optimisation and timed intercourse
Weight, smoking, alcohol, and exercise modification; ovulation tracking. Effective in some couples without further intervention.
- Ovulation induction
Clomifene citrate or letrozole for anovulatory women. Frequently combined with intercourse timing or IUI.
- Surgical management of underlying conditions
Laparoscopy for endometriosis, hysteroscopy for uterine adhesions, varicocele repair in male factor — directed at correcting an identified cause before assisted reproduction.
Procedural
- Intrauterine insemination (IUI)
Concentrated sperm placed in the uterus around ovulation. Less invasive and less expensive than IVF; lower per-cycle success rate.
- IVF / ICSI · View procedure page
In-vitro fertilisation, with or without intracytoplasmic sperm injection. The standard ART option for tubal factor, severe male factor, advanced reproductive age, and after failed IUI cycles.
- Donor egg / sperm / embryo cycles
Treatment using donor gametes or embryos. Legal frameworks (anonymity, recognition, parentage) vary materially between jurisdictions and have implications for the resulting child.
- Surrogacy
Pregnancy carried by a surrogate. Legality and enforceability vary widely across countries; cross-border surrogacy carries significant legal complexity.
Surgical
- Tubal microsurgery
Microsurgical repair of fallopian-tube obstruction. Largely superseded by IVF for most indications but retained for selected cases of tubal disease.
- Endometriosis excision
Laparoscopic excision of endometriotic deposits to improve natural conception rates and reduce pain. May be performed before or alongside IVF.
Related procedures
Sources
- [1]ESHRE — Guidelines for Good Practice in IVF Laboratories — eshre.eu(accessed 2026-05-09)
- [2]Wikipedia — Infertility — en.wikipedia.org(accessed 2026-07-24)
- [3]ASRM — Practice Committee Documents — asrm.org(accessed 2026-05-09)
Sources marked “on file” are held by The Treatment Registry but are not publicly accessible.