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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Definition and initial assessment of subfertility

Obstetrics and gynaecology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Do not let routine fertility assessment obscure urgent disease

Subfertility is usually assessed electively, but current pain, bleeding or collapse may be an ectopic pregnancy, while a testicular mass, acute testicular pain, severe neurological symptoms or impending gonadotoxic treatment requires urgent action.

Action: Check pregnancy and physiological stability when clinically possible, use the relevant acute pathway for pregnancy complications or testicular emergencies, and expedite fertility-preservation referral before gonadotoxic treatment starts.

Overview

Define delayed conception inclusively, recognise when investigation should begin, assess both partners in parallel, and direct people promptly to the right generalist or specialist pathway.

A health-related fertility problem is not a single diagnosis. It may arise from ovulatory, tubal, uterine, endometriosis-related, male, combined or unexplained factors, and the probability of conception changes with time and age. NICE uses an operational threshold for formal investigation rather than implying that everyone who has not conceived by a particular date is biologically sterile. In the absence of a known cause, assess after 12 months of regular unprotected vaginal intercourse or after 6 artificial-insemination cycles. The pathway applies inclusively, regardless of sexual orientation, partnership status or gender identity.

Begin with the person's route to conception. Ask sensitively about whether vaginal intercourse is possible and acceptable, its frequency, erectile or ejaculatory difficulty, dyspareunia, vaginismus, donor sperm and home insemination. People unable to have vaginal intercourse should be offered a consultation about conception options, not told simply to keep trying. When donor sperm is being considered, treatment in an HFEA-licensed clinic supports screening, clinical safety and correct legal parenthood arrangements.

Practice

Two practice questions

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Obstetrics and gynaecologyOriginal SBA

When the investigation clock continues

A 31-year-old has had regular unprotected intercourse for 10 months and then an early miscarriage. There is no known fertility factor. Under current NICE guidance, how should the investigation timeframe be handled?

Choose one answer, then submit
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG257 defining infertility and initial assessment
  • NICE NG257 initial advice about delayed conception
  • NICE NG257 investigation and management strategies
  • NICE NG257 recommendations PDF
  • HFEA choosing a licensed fertility clinic

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom

Clarify duration without restarting the clock after a miscarriage or ectopic pregnancy. Ask about previous pregnancies and their outcomes for everyone whose gametes are involved, prior fertility treatment and previous paternity. Female-factor clues include irregular or absent periods, pelvic pain, endometriosis, pelvic inflammatory disease, ectopic pregnancy, recurrent ovarian surgery and abdominal or pelvic operations. Male-factor clues include undescended testes, post-pubertal mumps orchitis, testicular cancer, genital surgery, trauma, varicocele, loss of ejaculation and previous abnormal semen results.

Record age because ovarian quantity and oocyte competence decline, while male age has a smaller adverse association. NICE recommends specialist referral at presentation when the person trying to become pregnant is 36 or older, or when either partner has a suspected cause or predisposing factor. The same principle applies at younger ages with amenorrhoea, significant pelvic disease, severe male-factor history or treatment likely to damage gonads: waiting 12 months adds delay without diagnostic value.

A comprehensive medical review includes chronic illness, genetic and developmental history, infection risk, vaccinations, cervical screening where applicable and every prescribed, over-the-counter, recreational or performance-enhancing drug. Specifically ask about exogenous testosterone and anabolic steroids, which can suppress spermatogenesis, and medicines such as finasteride, GLP-1 receptor agonists, NSAIDs and some vaginal lubricants. Ask about smoking, alcohol, weight trajectory, dietary restriction, exercise, heat and occupational toxicants without presenting lifestyle as moral blame.

Examination is selective and consent based. Record blood pressure and BMI alongside weight trajectory and general endocrine features. In a person with ovaries, look for androgen excess, thyroid disease, galactorrhoea when indicated and pelvic findings suggested by symptoms. In a person with testes, examine testicular size and consistency, epididymides, vasa and clinically suspected varicocele, particularly after repeated abnormal semen analyses. Any pelvic or genital examination should have a clear purpose, explanation, privacy and chaperone choice.

Initial tests run in parallel rather than as a sequence in which one partner must first prove a problem. A semen analysis using WHO methods is the core male-factor test. Ask about cycle frequency and regularity, and confirm ovulation with appropriately timed mid-luteal progesterone during formal infertility investigation. Choose tubal testing according to pelvic risk; do not routinely request prolactin, thyroid function, post-coital mucus testing, AMH as a spontaneous-conception predictor or screening hysteroscopy.

Close the consultation with a shared plan: which tests are being ordered, when they must be timed, who will communicate results and what triggers specialist referral. Acknowledge that fertility uncertainty, sexual difficulty, repeated testing and treatment can cause major psychological strain. NICE recommends counselling before, during and after investigation, provided by someone not directly managing the fertility treatment. Safety-net acute symptoms and remain alert to coercion, reproductive control, sexual abuse and safeguarding concerns.

Key points

  • NICE NG257 defines the practical investigation threshold by time trying: usually 12 months of regular unprotected vaginal intercourse, or 6 unsuccessful artificial-insemination cycles, when no cause is already suspected.
  • Do not wait for a time threshold when the person trying to become pregnant is 36 or older, either partner has a known or suspected cause, or there is a relevant predisposing history.
  • A miscarriage or ectopic pregnancy during the qualifying interval does not reset the clock; continue counting the original timeframe.
  • Assess both partners concurrently where conception is attempted with partner sperm; a normal result in one person does not remove the need to assess the other.
  • Regular vaginal intercourse every 2 to 3 days optimises the chance of conception; artificial insemination should be timed around ovulation.
  • Over 80% of heterosexual couples in the general population conceive within 1 year when the woman is under 40 and intercourse is regular without contraception; about half of the remainder conceive in year 2.
  • The opening assessment covers reproductive, sexual, medical, surgical, medicine, family, lifestyle and occupational history, followed by targeted examination and parallel semen and ovulation-focused testing.
  • Offer evidence-based information and independent counselling before, during and after investigation or treatment, irrespective of outcome.

Aetiology

01

Ovulatory and ovarian factors

PCOS, hypothalamic-pituitary disease, hyperprolactinaemia, diminished ovarian function and age-related decline can reduce or prevent release of a competent oocyte.

02

Tubal, uterine and pelvic factors

Tubal occlusion, hydrosalpinx, endometriosis, adhesions and selected uterine abnormalities can impair gamete transport, fertilisation, embryo transit or implantation.

03

Male factors

Impaired sperm production, obstruction, ejaculation problems, endocrine or genetic disease and treatment-related gonadal damage may alter sperm availability or function.

04

Combined or unexplained factors

More than one modest abnormality may coexist, while a complete standard evaluation can remain normal despite persistent failure to conceive.

Pathophysiology

  1. 1
    Reduced encounter probability

    Infrequent ovulation, mistimed sperm exposure, tubal blockade or sexual dysfunction reduces the opportunity for oocyte and sperm to meet.

  2. 2
    Gamete quantity or competence

    Oocyte competence changes with age and sperm concentration, motility or morphology may reduce fertilisation probability without creating an absolute binary threshold.

  3. 3
    Pelvic environment

    Inflammation, endometriosis, adhesions or hydrosalpinx can distort reproductive anatomy and adversely influence oocyte pickup, fertilisation, embryo transport or implantation.

  4. 4
    Time-dependent cumulative chance

    Monthly fecundability is limited even without disease, so cumulative non-conception becomes progressively more informative while age modifies prognosis.

Clinical features and red flags

Time-threshold presentation

No conception after 12 months of regular unprotected vaginal intercourse or 6 cycles of artificial insemination, with no known cause, meets the usual threshold for formal assessment.

Earlier female-factor signal

Age 36 or over, amenorrhoea, irregular cycles, pelvic pain, endometriosis, previous ectopic pregnancy, pelvic inflammatory disease or extensive pelvic surgery warrants referral without waiting a year.

Earlier male-factor signal

Undescended or atrophic testes, torsion or trauma, post-pubertal orchitis, testicular cancer treatment, genital surgery, loss of ejaculation or a clinically significant varicocele justifies prompt assessment.

Sexual or route-to-conception barrier

Erectile or ejaculatory dysfunction, dyspareunia, vaginismus, disability or inability to have vaginal intercourse requires sensitive consultation about treatment and insemination options.

Iatrogenic risk

Planned gonadotoxic systemic treatment, pelvic radiotherapy or gonadal surgery creates a time-critical opportunity for fertility preservation before exposure.

Red flags requiring action

  • A positive pregnancy test with unilateral pelvic pain, shoulder-tip pain, bleeding, syncope, shock or peritoneal signs requires urgent assessment for ectopic pregnancy.
  • Sudden severe testicular pain, a high-riding testis or nausea is testicular torsion until excluded and needs immediate surgical assessment rather than a routine fertility referral.
  • A hard intratesticular lump, progressive unilateral enlargement or a persistent unexplained testicular abnormality needs urgent suspected-cancer evaluation.
  • New visual-field disturbance, severe headache, ophthalmoplegia, vomiting or other focal neurological change with menstrual disturbance can indicate a sellar mass and warrants urgent assessment.
  • Chemotherapy, pelvic radiotherapy, gonadectomy or another treatment likely to impair fertility should trigger an expedited preservation discussion before treatment whenever clinically possible.

Investigations

  1. 01
    Parallel reproductive historyFirst step
    Why
    Define duration, route to conception and risk factors in everyone contributing gametes.
    Interpretation and limitations
    A known cause, age 36 or over in the person trying to become pregnant, or a predisposing history moves the case directly to specialist assessment rather than a further waiting period.
  2. 02
    Semen analysis
    Why
    Screen semen volume, concentration, total count, motility, vitality and morphology using WHO laboratory methods.
    Interpretation and limitations
    An abnormal result requires confirmation, ideally after about 3 months unless azoospermia or severe oligozoospermia warrants an earlier repeat; it does not diagnose absolute infertility on its own.
  3. 03
    Cycle assessment and mid-luteal progesterone
    Why
    Identify likely ovulatory dysfunction and biochemically confirm ovulation during infertility investigation.
    Interpretation and limitations
    Regular monthly cycles make ovulation likely, but NICE still recommends a mid-luteal progesterone; time it about 7 days before the expected period rather than automatically using day 21 in every cycle.
  4. 04
    Tubal assessment selected by history
    Why
    Determine whether at least one fallopian tube is patent and identify relevant pelvic pathology.
    Interpretation and limitations
    Use HSG or expert HyCoSy when there is no pelvic comorbidity; use laparoscopy and dye when endometriosis, previous PID or ectopic pregnancy makes simultaneous pelvic assessment important.
  5. 05
    Targeted endocrine and infection tests
    Why
    Investigate specific symptoms and make planned instrumentation or treatment safe.
    Interpretation and limitations
    Request prolactin only for ovulatory disorder, galactorrhoea or pituitary tumour; thyroid tests only with symptoms; screen for chlamydia before uterine instrumentation and test HIV, hepatitis B and C before IVF.
  6. 06
    Pregnancy testing when clinically relevant
    Why
    Separate delayed conception from a current pregnancy and triage pain or bleeding safely.
    Interpretation and limitations
    A positive hCG with pain, bleeding or instability requires urgent pregnancy localisation; an early loss during the fertility timeframe does not reset the eligibility interval.

Differential diagnosis

01

Normal time to conception

Most younger couples conceive within a year, but several normal cycles may pass because conception is probabilistic rather than guaranteed each month.

02

Ovulatory disorder

Irregular or absent menstruation, androgen excess or endocrine symptoms suggest that oocyte release is inconsistent or absent.

03

Tubal or endometriosis-related disease

Prior PID, ectopic pregnancy, pelvic surgery, severe dysmenorrhoea or deep dyspareunia raises pre-test probability of pelvic pathology.

04

Male-factor infertility

A relevant testicular, endocrine, genetic, treatment or ejaculation history directs prompt semen analysis and focused specialist assessment.

05

Sexual dysfunction or route barrier

Pain, vaginismus, erectile or ejaculatory difficulty and practical insemination problems may reduce sperm exposure despite otherwise normal reproductive physiology.

Management

01Opening consultationDefine the route, time and urgencyFirst stepA person or couple is concerned about delayed conception.+
  1. 1Establish who is trying to conceive, whose gametes are involved, the method and frequency of attempts, duration, pregnancy history and whether intercourse or insemination is difficult.
  2. 2Look immediately for age-related urgency, known reproductive disease, gonadotoxic treatment, acute pregnancy symptoms, testicular emergency and safeguarding concerns.
  3. 3Explain realistic population probabilities, advise intercourse every 2 to 3 days or insemination around ovulation, and agree when formal tests start.
02Parallel assessmentInvestigate both sides of conceptionThe formal threshold is met or an earlier-referral factor is present.+
  1. 1Take complete reproductive, sexual, medical, surgical, medicine, family, lifestyle and occupational histories from each relevant person.
  2. 2Arrange semen analysis alongside cycle and ovulation assessment, then select tubal, uterine, endocrine, genetic or infection tests from the clinical pattern.
  3. 3Review results together, recognise combined factors and avoid attributing delay to one borderline result before the assessment is complete.
03Specialist referralRefer without avoidable waitingFirst lineThe person trying to become pregnant is 36 or older, a cause is suspected, first-line tests are abnormal or treatment is likely to impair fertility.+
  1. 1Send a concise referral with duration, pregnancy history, relevant operations and treatments, cycle details, semen results and tests already completed.
  2. 2Expedite fertility-preservation assessment before gonadotoxic treatment and coordinate with oncology or the treating specialty so referral does not delay essential care.
  3. 3Explain that NHS treatment recommendations and locally commissioned access are related but not identical, and offer independent counselling while decisions are made.
04Unexplained findingsUse a positive diagnosis of exclusionOvulation, semen and tubal assessment do not reveal a cause.+
  1. 1Confirm that the core evaluation was complete and appropriately timed rather than ordering indiscriminate add-on tests.
  2. 2Consider coeliac serology in unexplained subfertility and address relevant health or lifestyle issues without implying causation.
  3. 3Discuss expectant management and current NG257 treatment thresholds using total time already trying, including time before assessment.

Complications

01

Psychological and relationship distress

Uncertainty, repeated loss, timed intercourse and invasive treatment can cause anxiety, low mood, sexual strain and social isolation.

02

Age-related loss of opportunity

Unnecessary sequential testing or inappropriate waiting can reduce the chance of success as ovarian age advances.

03

Treatment-associated harm

Poorly selected or monitored therapy can cause multiple pregnancy, OHSS, procedural complications, emotional distress and avoidable financial burden.

04

Missed underlying disease

Treating delayed conception as an isolated fertility issue can overlook endocrine disease, genetic conditions, malignancy or chronic infection.

Monitoring and follow-up

  • Track total time trying to conceive and do not reset it after miscarriage or ectopic pregnancy within the relevant NG257 timeframe.
  • Review whether intercourse or insemination frequency is sustainable and whether pain, sexual dysfunction or relationship strain needs separate treatment.
  • Record the result and timing of each core test, arranging prompt confirmation of abnormal semen analysis and correctly timed progesterone where needed.
  • Reassess urgency if age advances, cycles become irregular, new pelvic or testicular symptoms appear, or gonadotoxic treatment is proposed.
  • Confirm who will give results, make the referral and provide counselling so that parallel tests do not become fragmented care.

Special situations

The clock does not restart

NICE NG257 explicitly keeps the original investigation or expectant-management timeframe after a miscarriage or ectopic pregnancy, preventing an avoidable additional delay.

Assess in parallel

Semen and ovulatory or tubal factors can coexist; sequentially exhausting one partner's tests before assessing the other wastes time and can reinforce blame.

A threshold is not sterility

The 12-month definition determines when investigation becomes justified; it does not mean spontaneous conception is impossible after that point.

Inclusive history changes care

Partnership, anatomy, gametes, sexual practice and intended parenthood determine the useful questions and tests more accurately than assumptions based on identity.

Known cause means no wait

Amenorrhoea, significant tubal risk or a major testicular history already supplies a clinical reason for delay, so the usual one-year period is unnecessary.

Common pitfalls

  1. 01

    Restarting a 12-month or 2-year timeframe after an early pregnancy loss despite the explicit 2026 NICE recommendation not to do so.

  2. 02

    Investigating only the person trying to become pregnant and postponing semen analysis until every female-factor test is complete.

  3. 03

    Applying a 12-month wait to someone aged 36 or over or to either partner with a known or suspected fertility factor.

  4. 04

    Assuming vaginal intercourse is possible, desired or the route being used, rather than asking privately and offering appropriate options.

  5. 05

    Ordering broad endocrine, immunological or fertility add-on panels instead of hypothesis-led core assessment.

  6. 06

    Presenting local NHS funding rules as the biological definition of infertility or as a substitute for clinical referral.