What might be in the way, and what can be done.

Most fertility problems come down to a handful of causes. Each page below explains how the condition is found, what it changes, and which treatments help.

All 23 conditions, in one place.

Diabetes and fertility

Diabetes does not stop most people conceiving, but high blood sugar around conception raises the risk of miscarriage and birth defects.

Ectopic pregnancy

An ectopic pregnancy grows outside the womb, most often in a fallopian tube, and cannot continue.

Ejaculation problems

Ejaculation problems include premature, delayed, retrograde (semen goes into the bladder) and absent ejaculation.

Endometriosis

Endometriosis is tissue like the womb lining growing outside the womb. The WHO estimates it affects about 1 in 10 women of reproductive age.

Erectile dysfunction

Erectile dysfunction (ED) means difficulty getting or keeping an erection firm enough for sex.

Fallopian tube problems

Blocked or damaged fallopian tubes are a common cause of female infertility, and they usually cause no symptoms.

Fibroids, polyps and other uterine problems

Fibroids, polyps, scarring (adhesions), adenomyosis and a septum can affect fertility, mostly when they change the inside of the womb.

Genetic and chromosomal conditions

Genetic testing before IVF is needed only for some couples: after recurrent miscarriage, with a family history of a genetic condition, when both partners carry the same condition, or with a very low sperm count.

Hydrosalpinx

A hydrosalpinx is a fallopian tube blocked at its far end and filled with fluid. The fluid can leak into the womb and lowers the chance of an embryo implanting.

Irregular periods and ovulation problems

Irregular periods, cycles shorter than 21 days or longer than 35, usually mean ovulation is irregular or missing.

Low AMH and low egg reserve

AMH is a blood test that estimates how many eggs remain in the ovaries. A low AMH means fewer eggs in one IVF cycle.

Low sperm count

A low sperm count (oligospermia) means fewer than 16 million sperm per ml of semen, or fewer than 39 million in total, the WHO 2021 lower limits.

Male infertility

Male infertility means a problem with sperm numbers, movement, shape or delivery that lowers the chance of pregnancy.

Non-obstructive azoospermia

Non-obstructive azoospermia means no sperm in the semen because the testes make little or none, not because of a blockage.

Obstructive azoospermia

Obstructive azoospermia means there is no sperm in the semen because a tube is blocked or missing, while the testes usually make sperm normally.

PCOS

PCOS (polycystic ovary syndrome, renamed PMOS in 2026) is a common hormonal condition that stops or delays ovulation. It makes pregnancy harder, not impossible.

Recurrent implantation failure

Recurrent implantation failure means good-quality embryos have been transferred several times without a pregnancy.

Recurrent miscarriage

Recurrent miscarriage means losing two or more pregnancies.

Secondary infertility

Secondary infertility means difficulty getting pregnant after a previous pregnancy.

Thyroid and fertility

Thyroid problems can cause irregular ovulation and raise the risk of miscarriage, but a simple TSH blood test finds them and tablets usually correct them.

Unexplained infertility

Unexplained infertility means a couple has not conceived after a year of trying, yet standard tests are normal: ovulation, open tubes, egg reserve and semen analysis.

Varicocele

A varicocele is a group of swollen veins above the testicle, usually on the left. It is common and many men with one father children naturally.

Weight and fertility

Being overweight or underweight can disturb ovulation, lower sperm quality, make fertility treatment harder and raise pregnancy risks, in both partners.