Diagnostic Criteria for Infertility
Infertility is diagnosed when a sexually active couple using no contraception fails to achieve spontaneous pregnancy after 12 consecutive months of regular, unprotected intercourse. 1
Standard Diagnostic Threshold
- The 12-month criterion applies to couples where the female partner is under 35 years of age 1, 2
- Approximately 15% of couples meet this definition and seek medical treatment 1, 3
- This timeframe is supported by the European Association of Urology (2025) as a strong recommendation for performing infertility evaluation 1
Modified Criteria Requiring Earlier Evaluation (6 Months)
For women aged 35 years or older, evaluation should begin after only 6 months of unsuccessful attempts, not the standard 12 months 2, 4, 5. This modification is critical because:
- Age-related decline in fertility accelerates after 35 years 2
- Delayed evaluation in this population directly impacts treatment success and pregnancy outcomes 2
Additional Indications for Early Evaluation (Before 12 Months)
Evaluation should not wait 12 months in the following scenarios 2, 6:
- History of oligo-amenorrhea (infrequent or irregular menstruation) 2
- Known or suspected tubal disease (history of pelvic inflammatory disease, chlamydia infection, or prior pelvic surgery) 2, 6
- Known or suspected endometriosis 2, 6
- Known or suspected uterine abnormalities 2
- Identified subfertile male partner (prior abnormal semen analysis) 6
Bilateral Partner Evaluation
Both partners must be investigated simultaneously to properly categorize the cause of infertility 1, 2. This is a strong recommendation from the European Association of Urology 1. The rationale includes:
- Male-associated factors are found in approximately 50% of involuntarily childless couples 1
- Male factor is the sole or contributing cause in up to 40% of infertile couples 7, 5
- Concurrent evaluation prevents delays and unnecessary female-only interventions 1
Primary vs. Secondary Infertility
The definition applies to both 1:
- Primary infertility: Affects one in eight couples attempting to conceive their first child 1
- Secondary infertility: Affects one in six couples attempting subsequent children 1
Common Pitfalls to Avoid
- Do not delay evaluation in women over 35 years waiting for the full 12 months—this directly compromises outcomes 2, 4
- Do not evaluate only the female partner—male factors contribute to half of all cases and require concurrent assessment 1
- Do not assume fertility based on prior pregnancies—secondary infertility is distinct and requires full evaluation 1
- Do not overlook lifestyle factors (smoking, obesity, high caffeine intake >5 cups/day, alcohol) that reduce fertility and should be addressed during initial evaluation 2, 6
Clinical Context
While the 12-month definition is standard, approximately 85% of couples without infertility conceive within this timeframe, with most pregnancies occurring in the first 6 cycles 3, 8. After 12 unsuccessful cycles, untreated couples still have approximately 55% live birth rates over the next 36 months, but this probability declines significantly with advancing female age 8. This natural history supports the rationale for earlier intervention in women over 35 years and those with identifiable risk factors 2, 4.