Female Infertility and Subfertility

Female infertility is the failure to achieve a clinical pregnancy after a defined period of regular unprotected intercourse attributable, wholly or partly, to factors in the female partner. Subfertility describes reduced but not absent fecundity. The condition is approached as a couple-level problem with multiple possible female contributions, principally disorders of ovulation, tubal or pelvic disease, uterine factors, and age-related decline in ovarian reserve.

Definition

Female infertility is the inability to achieve a clinical pregnancy after 12 months or more of regular unprotected intercourse (or after 6 months in women over 35) owing to factors in the female partner, with subfertility denoting diminished rather than absent fertility.

Scope

This entry covers how female infertility is defined, the main categories of female-factor causes, the concept of ovarian reserve, and the place of the condition within reproductive medicine. It is a reference subject; it summarizes mechanisms and evidence and does not provide an individualized diagnostic work-up or treatment plan.

Key concepts

• Ovulatory dysfunction (including polycystic ovary syndrome)
• Tubal and pelvic factor infertility
• Uterine and endometrial factors
• Ovarian reserve and reproductive ageing
• Diminished ovarian reserve
• Couple-level evaluation
• Primary and secondary infertility

Mechanisms

Female fertility depends on regular ovulation, patent fallopian tubes, a receptive uterus and endometrium, and an adequate pool of competent oocytes. Disruption at any of these points reduces fecundity. Ovulatory disorders, of which polycystic ovary syndrome is the most common, interrupt the cyclic release of a mature oocyte; tubal disease, often a sequel of pelvic infection or endometriosis, blocks the meeting of egg and sperm; and uterine factors impair implantation. Independently, ovarian reserve declines with age as both the number and the quality of oocytes fall, which is why female age is a dominant determinant of fecundity. Measures such as antral follicle count and anti-Mullerian hormone estimate the remaining follicular pool rather than guaranteeing or excluding conception.

Clinical relevance

Infertility is a common reason couples seek gynecologic and reproductive-medicine care, and its evaluation is shared between the partners. This entry describes the categories of female factor and the meaning of ovarian-reserve testing for reference; it is not a diagnostic protocol, and the timing and nature of any evaluation or treatment are matters for current clinical guidelines and individual assessment.

Epidemiology

Infertility affects a substantial minority of couples of reproductive age worldwide, with female, male, combined, and unexplained factors each contributing. Prevalence estimates vary with the definition used and the population studied, and access to care differs markedly across regions, a disparity emphasized in global reviews of infertility.

Evidence & guidelines

The American Society for Reproductive Medicine and equivalent bodies define infertility and issue committee opinions on its evaluation, including the interpretation of ovarian-reserve tests. These sources frame the standardized definitions and caution that ovarian-reserve measures predict response and reproductive ageing rather than absolute fertility.

Debates

How should ovarian-reserve tests be interpreted?

Markers such as anti-Mullerian hormone and antral follicle count estimate the size of the remaining follicle pool and predicted response to stimulation, but they are imperfect predictors of natural conception, so professional guidance warns against using a single value to declare a woman fertile or infertile.

Seminal works

• asrm-definitions-2013
• inhorn-2015
• penzias-2020

Frequently asked questions

What is the difference between infertility and subfertility?

Infertility is conventionally defined as failure to conceive after 12 months (or 6 months over age 35) of regular unprotected intercourse; subfertility describes reduced fecundity in couples who may still conceive, sometimes with more time or assistance.

Does a low ovarian-reserve test mean a woman cannot conceive?

No. Ovarian-reserve markers estimate the remaining follicle pool and likely response to stimulation; professional guidance states they are not reliable standalone predictors of natural conception.