Infertility
Infertility means that pregnancy has not occurred after a sustained period of regular unprotected intercourse. It can arise from female factors, male factors, a combination of both, or remain unexplained after standard testing.
At a glance
Quick facts
- Definition
- No pregnancy after 12 months of regular unprotected intercourse
- Can affect
- Either reproductive partner
- Common evaluation
- Ovulation, tubes/uterus and semen
- Earlier review
- Often appropriate with age or known risk factors
- Treatment
- Cause-directed care, IUI or IVF when appropriate
- Global burden
- About 1 in 6 people experience infertility in their lifetime
Dr. Farida Sani
Fertility Physician · Clearview Hospital and Fertility
Reviewed for clinical accuracy, fertility context and patient-facing clarity.
Names & terminology
How this entity may be named or searched
- Infertility
- WHO defines infertility as failure to achieve pregnancy after 12 months or more of regular unprotected sexual intercourse.
- Primary infertility
- No pregnancy has previously been achieved.
- Secondary infertility
- Difficulty achieving pregnancy after at least one previous pregnancy.
- Subfertility
- A term often used for reduced fertility; definitions and usage vary across settings.
Structured entity profile
Clinical profile
Overview
WHO defines infertility as a disease of the male or female reproductive system marked by failure to achieve pregnancy after 12 months or more of regular unprotected sexual intercourse. It may be primary, when no pregnancy has previously been achieved, or secondary, after at least one previous pregnancy. [1]
Infertility is not automatically a “female problem”. Causes can involve ovulation, the ovaries, uterus or fallopian tubes, sperm production or delivery, sexual or ejaculatory function, or a combination of factors. Sometimes a standard evaluation finds no clear explanation. WHO estimates that about one in six people of reproductive age experience infertility during their lifetime. [1] [2]
Symptoms and warning signs
The usual sign is not conceiving within the expected time rather than a specific symptom. Clues to an underlying cause can include very irregular or absent periods, pelvic pain, prior pelvic infection or surgery, sexual or ejaculatory difficulty, testicular problems, or a history of treatment that can impair fertility. Many people have no other symptoms. [1] [3]
SYMPTOM MATRIX
Fertility clues come from both partners
Many fertility problems are silent, so absence of symptoms does not rule out a male or female factor.
- Pregnancy has not occurred despite regular attempts
- No specific symptoms in either partner
- Questions about age and duration of trying
- Need for coordinated assessment of both partners
- Irregular or absent periods
- Pelvic pain or previous pelvic infection
- Abnormal semen result
- Sexual or ejaculatory difficulty
- Previous pelvic/testicular surgery or gonadotoxic treatment
- Known condition strongly associated with infertility
- Markedly irregular or absent cycles
- History suggesting severe male factor
- Older reproductive age where delay may reduce options
The timing of assessment should be individualized rather than waiting automatically for 12 months when a known risk factor is present.
Diagnosis
A fertility evaluation aims to identify treatable factors without unnecessary delay or testing. ASRM recommends evaluation after 12 months of trying when the female partner is under 35, after 6 months from age 35, and potentially more immediately over age 40 or when a known condition associated with infertility is present. Local pathways differ, but the principle of earlier assessment when delay matters is widely used. [3]
Standard assessment includes reproductive and medical history, review of menstrual regularity and ovulation, evaluation of the female reproductive tract and tubal patency when indicated, and semen analysis of the male partner. NICE recommends repeating an abnormal semen analysis and emphasizes parallel assessment rather than focusing only on one partner. [3] [4]
Diagnostic pathway
Build a couple-level fertility picture
A stepwise assessment looks for common, treatable causes before moving to more invasive testing.
Fertility assessment is usually most useful when relevant male and female factors are evaluated in parallel.
Common causes of infertility
Female-factor infertility may involve ovulatory disorders, tubal damage, endometriosis, uterine abnormalities or reduced ovarian function. Male factors include low sperm number or movement, abnormal sperm production, obstruction, endocrine disorders and problems with ejaculation. Lifestyle and environmental exposures can also affect reproductive health. [1]
Some couples have more than one factor, and some are classified as unexplained after standard testing. A label of unexplained infertility means that routine evaluation has not identified a cause; it does not mean the difficulty conceiving is imaginary or that pregnancy is impossible. [2]
Treatment and management
Treatment is matched to the cause, age, duration of infertility and reproductive goals. Examples include treating endocrine causes of anovulation, surgery in selected uterine or tubal conditions, treatment of specific male-factor conditions, ovulation induction, intrauterine insemination (IUI) and in vitro fertilisation (IVF). [2] [4]
Not every patient moves directly to IVF. The appropriate sequence can include expectant management, lower-complexity treatment or assisted reproduction depending on prognosis and diagnosis. Counselling should include realistic success rates, time, cost, treatment burden and risks such as multiple pregnancy or ovarian hyperstimulation where relevant. [2]
Treatment & care hub
Match treatment to the factor that limits conception
Fertility treatment is a pathway rather than a single procedure.
Treat a specific underlying problem
Endocrine, structural, infectious or selected male-factor causes may have targeted treatment.
Increase sperm delivery to the uterus
IUI may be used in defined fertility scenarios, sometimes with ovarian stimulation.
Fertilisation outside the body
IVF can bypass tubal disease and is used for many other fertility indications depending on prognosis.
Address emotional and practical burden
Decision-making should include psychological wellbeing, finances, time and treatment preferences.
Treatment is individualized according to diagnosis, age, reproductive goals and clinical context.
When to seek fertility assessment
The 12-month definition is useful, but it is not a rule that everyone must wait a full year. Earlier assessment can be appropriate with older reproductive age, irregular or absent cycles, known tubal or uterine disease, endometriosis, previous chemotherapy or pelvic surgery, or a known male-factor problem. [3]
A common timing rule is evaluation after 12 months of trying when the female partner is under 35, and after 6 months when she is 35 or older; assessment should be earlier when a known fertility-related condition is present.
Evidence snapshot
Infertility is common worldwide
WHO estimates show that infertility is not a rare problem and occurs across countries and income groups.
Common questions
Frequently asked questions
WHO defines infertility as failure to achieve pregnancy after 12 months or more of regular unprotected sexual intercourse, although assessment may begin earlier when age or medical history makes delay inappropriate.
Yes when applicable. Fertility assessment should consider male and female factors in parallel because either or both may contribute.
No. Treatment depends on the cause and may include expectant management, medicines, surgery, IUI or IVF.
It means standard fertility testing has not identified a specific cause. It does not mean the fertility problem is not real.
Yes. Secondary infertility describes difficulty achieving another pregnancy after at least one previous pregnancy has occurred.
Sources
- WHO — Infertility fact sheet, 28 November 2025
- WHO — Guideline for the prevention, diagnosis and treatment of infertility, 2025
- ASRM — Fertility evaluation of infertile women: a committee opinion, 2021
- NICE — Fertility problems: assessment and treatment (NG257) - investigation, 2026
This article is based on trusted medical sources and has undergone clinician review. It is not a substitute for personalized medical advice.
Male factors are part of the infertility evaluation and include not only sperm number and motility but also morphology and other semen abnormalities.