Unexplained infertility: what it means, tests and the options

The NHS describes infertility as a couple being unable to get pregnant despite regular unprotected sex, and says around 1 in 7 couples may have difficulty conceiving. For 1 in 4 couples a cause cannot be identified. In the UK, it explains, unexplained infertility is when no cause can be found in either partner, and it accounts for around 1 in 4 cases.

The label is a statement about the limits of testing, not about the future. The investigations the NHS describes look at ovulation, the fallopian tubes and womb, and semen quality. The NHS suggests that if a cause has not been found you talk to your doctor about the next steps.

The NHS says more than 8 in 10 couples, where the woman is under 40, will conceive naturally within a year if they have regular unprotected sex, defined as every 2 to 3 days, and that of those who do not conceive in the first year, about half will conceive in the second year. For couples who have been trying for more than 3 years without success, the likelihood of getting pregnant naturally within the next year is 1 in 4, or less.

You should see a GP if you have not conceived after a year of trying, and sooner if the woman is aged 36 or over, because the decline in fertility speeds up in the mid-30s, or if there is another reason for concern such as cancer treatment in the past or possible sexually transmitted infection. The NHS says it is best for both partners to attend, as problems can affect either or both. Infertility is usually only diagnosed and treated when a couple have not conceived after 2 years of trying.

After questions about medical and sexual history, previous pregnancies, how long you have been trying, contraception, medicines and lifestyle, the GP may carry out an examination and refer you or your partner for tests. The NHS lists the main ones.

The NHS lists factors that affect fertility, which are relevant even when no cause is found: age (fertility declines with age), weight (a BMI of 30 or over reduces fertility, and being severely underweight can affect ovulation in women), sexually transmitted infections, smoking including passive smoking, alcohol, environmental exposure to certain pesticides, solvents and metals, and stress. The safest approach to alcohol when trying for a baby is none, and the UK chief medical officers advise adults to drink no more than 14 units a week.

The GP may recommend lifestyle changes to improve your chances. These are worth making, but it is important to avoid self-blame; the NHS notes that stress is only one factor and that supporting each other matters during an emotional process.

The NHS says treatment depends on the cause and on what your local integrated care board (ICB) funds. For unexplained infertility two points stand out. First, the NHS says medicine that stimulates the ovaries is not recommended for women with unexplained infertility because it has not been found to increase their chances of getting pregnant. Second, it says NICE recommends that women with unexplained infertility who have not conceived after 2 years of regular unprotected sex should be offered IVF.

The NHS describes IUI as inserting washed sperm into the womb through a thin tube, and IVF as taking fertility medicine to produce more eggs, removing eggs, fertilising them with sperm in a laboratory and returning an embryo to the womb. The HFEA describes IVF as suitable for people with a wide range of fertility issues and one of the most commonly used treatments, and describes lower-intervention options such as natural IVF, mild stimulation IVF and in vitro maturation.

IVF can cause complications: the NHS lists multiple pregnancy when more than one embryo is placed, which significantly increases risks for you and your babies, and a slightly increased risk of ectopic pregnancy. NICE guidance on fertility problems was updated and replaced by guideline NG257, so ask your clinician which current recommendations apply to you.

The NHS says fertility treatment funded by the NHS varies across the UK, waiting lists can be very long in some areas, and eligibility criteria vary; a GP can advise or you can contact your local ICB. If the GP refers you for further tests, the NHS pays for this, and all patients have the right to be referred to an NHS clinic for the initial investigation.

Private treatment is available, but the NHS cautions that it can be expensive, there is no guarantee of success and it is important to choose a clinic carefully. It advises asking your GP for advice and choosing a clinic licensed by the Human Fertilisation and Embryology Authority (HFEA). Ask for a clear itemised plan, what add-ons are proposed and what evidence supports each, how many embryos would be transferred, and what is included if a cycle is cancelled.

Not having an explanation can be harder than having a diagnosis, because there is no obvious thing to fix. The NHS acknowledges that trying to conceive can be an emotional process and encourages partners to support each other. Many people find talking to others in the same position helpful. If low mood or relationship strain builds, tell your GP.