Infertility

What is it?

The WHO defines infertility as “a disease of the male or female reproductive system” manifested by the failure to achieve a pregnancy after 12 months or more of regular unprotected sexual intercourse. It is “primary” if there has never been a pregnancy, and “secondary” if there has been at least one previous pregnancy. The NHS uses the same division.

According to the NICHD a couple is described as infertile if pregnancy has not occurred after a year of regular intercourse without contraception, or after 6 months if the woman is over 35; the term may also include inability to carry a pregnancy to term because of miscarriage or stillbirth, which MedlinePlus also mentions. The NICHD distinguishes it from “subfertility”, in which pregnancy is likely to occur without medical intervention but takes longer than usual.

Figures by source: the WHO estimates that about one in 6 people of reproductive age worldwide experiences infertility in their lifetime. The NICHD states that about 9% of men and 11% of women of reproductive age in the United States have had fertility problems. The NHS estimates that about 1 in 7 couples have difficulty conceiving. These figures differ between countries and methods of measurement.

Natural chances of conception: the NHS states that more than 8 in 10 couples (when the woman is under 40) conceive naturally within a year with regular intercourse every two or three days. According to the NICHD, pregnancy occurs in 40% to 60% of healthy couples under 30 within the first three months, while 12% to 15% do not conceive after a year, and about 10% after two years.

Causes

The NICHD stresses that “the problem is as likely to be in the man as in the woman”, and that the cause may be a combination of both. Cases are roughly divided: a third due to a factor in the man, a third due to a factor in the woman, and a third a combined or unknown cause (NICHD, MedlinePlus). The CDC says: “both men and women can contribute to infertility”.

Causes in the woman — ovulation: according to the NICHD, failure of ovulation is the most common cause and accounts for about 40% of infertility in women, and its causes include polycystic ovary syndrome (one of the most common causes of infertility in women, which the CDC describes as the most common cause of ovulation disorders), primary ovarian insufficiency (POI) in which the ovary stops producing hormones and eggs early, declining egg reserve with age, and endocrine disorders. MedlinePlus also lists hormone imbalance.

Causes in the woman — structural and other: blocked or damaged fallopian tubes, which according to the WHO may result from untreated sexually transmitted infection, complications of unsafe abortion, postpartum sepsis, or abdominal and pelvic surgery; endometriosis — the NICHD states that 25% to 50% of women with infertility have this condition, and 30% to 40% of those who have it experience infertility; uterine fibroids (present in 5% to 10% of women with infertility according to the NICHD), polyps, scarring and abnormalities of uterine shape, and adenomyosis according to the CDC. The NICHD adds infections such as untreated chlamydia, gonorrhoea and syphilis, and some autoimmune diseases.

Causes in the man — sperm production: the NICHD states that the man contributes to about 40% of infertility in couples, and that varicocele is the most common cause of low sperm count and is present in about 40% of men with fertility problems. Other causes include: chromosomal defects (such as Klinefelter syndrome), diabetes and thyroid problems, undescended testicle, infections affecting the testicle (such as mumps, gonorrhoea and chlamydia), hormone imbalance including raised prolactin, and testicular injury. About 15% of infertile men have no sperm in their semen (azoospermia).

Causes in the man — sperm transport: according to the NICHD, transport problems account for 10% to 20% of male infertility, including blocked transport ducts, surgical cutting of the vas deferens (vasectomy), congenital absence of the ducts in people with cystic fibrosis, retrograde ejaculation into the bladder, and erectile dysfunction. The WHO summarises men's causes as problems with ejaculation of semen, absence or low number of sperm, or abnormalities in their shape and movement; MedlinePlus also lists a history of high fever or mumps and genetic disorders.

Unexplained infertility: when the cause is not known it is called “idiopathic”. The NICHD states that this occurs in about 30% of infertility in women and about 50% in men, and the NHS estimates that about 25% of cases have no identified cause. The NICHD explains that knowing the exact cause may not be necessary to start treatment that improves the chances of pregnancy.

Risk factors

Age in women: according to the NICHD a woman is born with all the eggs she will naturally have (thought to be 1 to 2 million), and the decline in fertility accelerates as the number and quality of eggs fall, so in the thirties it falls to about half of what it was in the early twenties and the chances of pregnancy clearly fall after 35. The CDC says a woman's chances of having a baby “decline rapidly every year after age 30”. With age the risk of miscarriage and embryos with abnormal chromosomes rises, and natural pregnancy does not occur after menopause (NICHD).

Age in men: the NICHD states that advancing age reduces the quality and number of sperm, and that the decline in a man's fertility is slower than a woman's. The CDC says couples in which the man is 40 or older report more difficulty conceiving.

Lifestyle: the WHO states that smoking, excessive alcohol and obesity may affect fertility. The NICHD adds marijuana and illicit drugs, and that obesity in men is linked to reduced sperm count and quality, and that severe underweight and excessive exercise may disturb ovulation in women. The NHS states that a body mass index of 30 or more reduces fertility, and that smoking (including second-hand smoke) reduces the chances of pregnancy and semen quality. The CDC adds severe overweight or underweight, and excessive physical or emotional stress that leads to absent periods.

Health and environmental factors: sexually transmitted infections including chlamydia (NHS); stress, which may affect the relationship between the couple and desire, and in severe cases ovulation and sperm production (NHS); and exposure to certain pesticides, solvents and metals (NHS). The NICHD states that hard physical work and some medicines may reduce sperm production, that high blood pressure may change their shape, and that chemotherapy and radiotherapy may cause infertility. The CDC adds testicular injury and repeated exposure of the testicles to high temperatures.

Symptoms

The main sign is failure to conceive within the period set in the definition (WHO, NICHD). This page does not cover a separate list of infertility symptoms, but the sources list signs that may indicate an underlying cause and call for earlier review: irregular or absent periods and very severe period pain (CDC, NICHD).

In men, signs linked to certain causes may appear such as erectile dysfunction or ejaculation problems (NICHD); in women, signs of polycystic ovary syndrome such as excess hair and acne may appear. Diagnosis remains for the doctor after examination.

How is it diagnosed?

When assessment begins: the NICHD and CDC advise seeing a care provider after a year of trying if the woman is under 35, and after 6 months if 35 or older, and the CDC says couples in which the woman is over 40 should consider faster assessment and treatment. The NHS states that women aged 36 and over should ask for help earlier. These are general periods that may differ between countries, and the doctor determines the suitable timing.

Assessment of the woman according to the NICHD: questions about previous pregnancies and miscarriages and regularity of periods, a pelvic examination and ultrasound imaging, a progesterone test around day 23 of the cycle to confirm ovulation, and FSH and AMH tests to estimate ovarian reserve. To examine the fallopian tubes and uterus: X-ray imaging after injecting dye through the cervix (hysterosalpingography), or laparoscopy, which may also treat a blockage, or transvaginal ultrasound, or hysteroscopy, or ultrasound of the uterus after introducing saline.

Assessment of the man according to the NICHD: clinical examination to look for inflammation, hernia, duct deformity, hormone deficiency, masses or varicocele, and semen analysis after about 48 hours of abstaining from ejaculation, and hormone tests (testosterone, FSH, thyroid and prolactin), a needle testicular biopsy, or genetic tests may be added if sperm are absent or very low.

The CDC states that initial assessment is chosen according to the couple's circumstances and may include semen analysis, evaluation of the fallopian tubes and an ovarian reserve test; MedlinePlus lists clinical examination, blood tests, imaging and semen analysis. Both partners are assessed together because both may contribute to the problem.

Treatment

The treatment categories usually used are listed here; this is not a prescription. The doctor chooses the plan according to each person's condition; do not change any medicine or dose without a specialist.

Treatment categories as the sources list them (determined by the doctor): the NICHD divides treatments into treatments for the man, treatments for the woman, assisted reproductive technologies, and treatment of diseases causing infertility; MedlinePlus lists treating the underlying cause, medicines, assisted reproductive technologies, and surgery; the CDC adds timing intercourse with ovulation (with or without medicines), which it says is often the first choice for many couples, and intrauterine insemination. According to the NICHD, 85% to 90% of cases are treated with conventional medical treatments such as medicines or surgery.

For the woman according to the NICHD and NHS: ovulation-stimulating medicines (oral tablets or injected hormones known as gonadotropins), medicines to lower raised prolactin; and surgeries to repair or unblock the fallopian tubes, remove endometriosis foci, and remove fibroids, polyps and scars. The NICHD states that the success of surgery to repair the tubes is low (about 20% depending on the surgeon's skill).

For the man according to the NICHD and MedlinePlus: medicines for some problems such as hormone imbalance and erectile dysfunction; surgery to repair blockage of the transport ducts or treat varicocele (the NICHD states that repairing varicocele may improve sperm quality but evidence has not shown it raises pregnancy rates); and assisted reproductive technologies when surgery is not enough.

Assisted reproductive technologies: the CDC defines them as all fertility treatments in which eggs or embryos are handled outside the body. The NICHD lists: intrauterine insemination (IUI) by placing specially prepared sperm in the uterus, whose success rate may reach 20% per cycle in the best conditions; in vitro fertilisation (IVF) with its four stages: ovarian stimulation, egg retrieval, fertilisation in the laboratory, and transfer of the embryo to the uterus; and intracytoplasmic sperm injection (ICSI) of a single sperm into the egg when ordinary fertilisation is not possible.

Treating causes: the NICHD lists for polycystic ovary syndrome weight loss, ovulation-stimulating medicines, medicines to improve insulin sensitivity, in vitro fertilisation and ovarian drilling surgery; for endometriosis surgery or assisted reproductive technologies; and that treating thyroid disorders may improve fertility. The doctor determines the plan suitable for each case, and no fertility medicine is started or stopped without their supervision.

Follow-up

Fertility treatments need medical supervision because they have risks: the NICHD states that ovulation-stimulating medicines raise the likelihood of multiple pregnancy, that about 30% of pregnancies with injected hormones (gonadotropins) are multiple, about two thirds of them twins; and that surgery on the fallopian tubes raises the risk of ectopic pregnancy. The NHS states that IVF slightly raises the risk of ectopic pregnancy. This page does not cover detailed follow-up schedules during treatment.

Before cancer treatment: the NICHD states that chemotherapy, radiotherapy and some surgeries may affect the fertility of men and women, and that there are ways to preserve fertility before treatment whose availability depends on the type of cancer and the urgency of treatment, so they are discussed with the care provider early.

Complications

Treatment-related complications: multiple pregnancy (including twins with IVF), and ectopic pregnancy, whose risk rises slightly with IVF according to the NHS. The NHS defines ectopic pregnancy as implantation of the fertilised egg outside the uterus, usually in a fallopian tube, and lists fertility treatments such as IVF among things that raise its risk.

Psychological and social impact: the WHO states that infertility may cause psychological distress, depression, anxiety and low self-esteem, and may expose women in particular to social stigma, violence and divorce. The NHS states that stress may affect the relationship between the couple and weaken desire.

As a woman's age rises, the risk of miscarriage and embryos with abnormal chromosomes increases (NICHD).

Prevention

The WHO lists preventable causes: untreated sexually transmitted infections, complications of unsafe abortion, and postpartum sepsis, and calls for raising fertility awareness and promoting a healthy lifestyle to reduce behavioural risks.

Lifestyle: quit smoking and avoid second-hand smoke, avoid alcohol (the NHS says the safest is not drinking at all to reduce the risk to the fetus), keep a healthy weight, and reduce exposure to certain pesticides, solvents and metals (NHS). The NICHD states that losing 5% of body weight in women with obesity and polycystic ovary syndrome clearly improves ovulation and chances of pregnancy.

Fertility preservation: before cancer treatment, ways to preserve fertility are discussed with the care provider (NICHD).

Living with it

MedlinePlus states that “many couples treated for infertility go on to have children”. The NHS states that the chance of natural pregnancy in the following year falls to 1 in 4 or less in those who have tried for more than 3 years, so not delaying assessment helps.

Coping with stress: infertility is a psychologically and socially exhausting experience according to the WHO, and stress may affect the relationship and desire (NHS). Since both partners may contribute to the problem (CDC), the couple is assessed together. The WHO points out that access to fertility care and IVF remains difficult and costly in many countries. This page does not cover psychological support in detail.

Common questions