Infertility primarily refer to the biological inability of a person to contribute to conception. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term. There are many biological causes of infertility, some which may be bypassed with medical intervention.

Women who are fertile experience a natural period of fertility before and during ovulation, and they are naturally infertile during the rest of the menstrual cycle. Fertility awareness methods are used to discern when these changes occur by tracking changes in cervical mucus or basal body temperature.

Definition

There are strict definitions of infertility used by many doctors. However, there are also similar terms, e.g. subfertility for a more benign condition and fecundity for the natural improbability to conceive. Infertility in a couple can be due to either the woman or the man, not necessarily both.

Infertility

Reproductive endocrinologists, the doctors specializing in infertility, consider a couple to be infertile if:

• the couple has not conceived after 12 months of contraceptive-free intercourse if the female is under the age of 34
• the couple has not conceived after 6 months of contraceptive-free intercourse if the female is over the age of 35 (declining egg quality of females over the age of 35 account for the age-based discrepancy as when to seek medical intervention)
• the female is incapable of carrying a pregnancy to term.

Subfertility

A couple that has tried unsuccessfully to have a child for a year or more is said to be subfertile meaning less fertile than a typical couple. The couple's fecundability rate is approximately 3-5%. Many of its causes are the same as those of infertility. Such causes could be endometriosis, or polycystic ovarian syndrome.

Primary vs. secondary infertility

Couples with primary infertility have never been able to conceive, while, on the other hand, secondary infertility is difficulty conceiving after already having conceived (and either carried the pregnancy to term, or had a miscarriage). Technically, secondary infertility is not present if there has been a change of partners.

Prevalence

• Generally, worldwide it is estimated that one in seven couples have problems conceiving, with the incidence similar in most countries independent of the level of the country's development.

• Fertility problems affect one in seven couples in the UK. Most couples (about 84 out of every 100) who have regular sexual intercourse (that is, every 2 to 3 days) and who do not use contraception will get pregnant within a year. About 92 out of 100 couples who are trying to get pregnant do so within 2 years. NICE fertility guidance