Infertility and Hormones

Infertility usually means not conceiving after a sustained period of trying without contraception. It is common, often involves both partners, and frequently has a hormonal element because reproduction depends on a finely tuned balance of chemical messengers. This page explains the possible links and why a clinician's assessment, for both partners, matters more than self-diagnosis.

How fertility can relate to hormones

Conception depends on a coordinated sequence of hormonal signals. In people who ovulate, the brain releases hormones that prompt the ovaries to mature and release an egg, and the resulting cycle prepares the womb lining for a possible pregnancy. In people who produce sperm, hormones from the brain drive the testes to make testosterone and sperm. When any step in these pathways is disrupted, fertility can be affected.

Because the hormonal control of reproduction is shared across the brain, the thyroid, the ovaries or testes, and other glands, a problem at any level can show up as difficulty conceiving. That is why infertility is best understood as a clue that prompts careful evaluation rather than a single diagnosis.

Which hormones and conditions may be involved

Many factors can contribute. None can be diagnosed from the difficulty alone, but a clinician may consider:

• Ovulation problems. Conditions such as polycystic ovary syndrome (PCOS) can disrupt the hormonal signals needed for regular ovulation.
• Thyroid hormones. Both an underactive and an overactive thyroid can affect menstrual cycles and fertility.
• Prolactin. A raised level of this hormone can interfere with ovulation and with sperm production.
• Testosterone and pituitary hormones. In people who produce sperm, low signalling from the brain or low testosterone can reduce sperm production.
• Age-related changes. The number and quality of eggs declines with age, which affects the chance of conceiving.

Non-hormonal causes to keep in mind

Fertility is not only about hormones. Blocked or damaged fallopian tubes, conditions affecting the womb, endometriosis, and structural problems can all play a part. In people who produce sperm, the number, movement, and shape of sperm matter, and these can be affected by blockages, past infections, varicoceles, and other factors. Weight, smoking, alcohol, certain medicines, and general health influence fertility in everyone. Because the picture is so varied, a clinician evaluates both partners and the couple together.

Tests a clinician might consider

Assessment usually begins with a history from both partners covering the menstrual cycle, general health, medicines, and how long conception has been attempted, along with an examination. Depending on the findings, a clinician might consider:

• Tests of ovulation using blood hormones measured at particular points in the cycle.
• Thyroid tests such as TSH and a prolactin measurement.
• A semen analysis to assess sperm number, movement, and shape, sometimes with hormone tests including testosterone.
• Imaging of the reproductive organs to check structure and tubal patency.

You can read more about individual tests in our blood tests section and about the messengers themselves in the hormones section. Related conditions are covered in the conditions section, and other symptoms are listed in the symptoms section.

When to see a clinician

It is reasonable to seek advice after about a year of trying to conceive without success, or sooner when periods are irregular or absent, when there is a known reproductive or hormonal condition, or when age or medical history suggests earlier assessment would help. A clinician can take a history from both partners, examine, arrange appropriate tests, and explain the options. This page is educational and is not a substitute for personalised medical advice.