Inform women, and trans men and non-binary people with female reproductive organs who are trying to become pregnant that drinking no more than 1 or 2 units of alcohol once or twice per week and avoiding episodes of intoxication reduces the risk of harming a developing fetus. Advise them that, according to the Chief Medical Officer's guidelines on alcohol, the safest approach is to avoid alcohol altogether. [2004, amended 2026]
Inform men, and trans women and non-binary people with male reproductive organs, that:
excessive alcohol intake is detrimental to semen quality
drinking within the limits of the weekly drinking guidance in the UK Chief Medical Officer's advice on low risk drinking (14 units per week), if spread across several days, for example, up to 2 units per day, is unlikely to affect their semen quality. [2004, amended 2026]
Inform women, and trans men and non-binary people with female reproductive organs who smoke, that this is likely to reduce their fertility. [2004]
Inform women, and trans men and non-binary people with female reproductive organs that passive smoking is likely to affect their chance of conceiving. [2004]
Inform men, and trans women and non-binary people with male reproductive organs who smoke that there is an association between smoking and reduced semen quality (although the impact of this on male fertility is uncertain), and that stopping smoking will improve their general health. [2004]
Encourage and support people to stop smoking as advised in NICE's guideline on tobacco: preventing uptake, promoting quitting and treating dependence. [2026]
Inform people who are concerned about their fertility that there is no consistent evidence of an association between consumption of caffeinated beverages (tea, coffee, energy drinks and colas) and fertility problems. [2004, amended 2026]
Inform women, and trans men and non-binary people with female reproductive organs who have a body mass index (BMI) of 30 kg/m2 or over:
that they are likely to take longer to conceive, and
that if they are not ovulating, losing weight is likely to increase their chance of conception. [2004, amended 2013]
Inform women, and trans men and non-binary people with female reproductive organs that participating in a group programme involving exercise and dietary advice leads to more pregnancies than weight loss advice alone. [2004, amended 2013]
Inform men, and trans women and non-binary people with male reproductive organs who have a BMI of 30 kg/m2 or over that they have an increased risk of reduced fertility. [2004, amended 2013]
For advice on preventing and managing overweight, obesity and central adiposity, see NICE's guideline on overweight and obesity management. [2026]
Advise women, and trans men and non-binary people with female reproductive organs who have a BMI of less than 18.5 kg/m2 and who have irregular menstruation or are not menstruating that increasing body weight is likely to improve their chance of conception. [2004, amended 2026]
Inform men, and trans women and non-binary people with male reproductive organs that there is an association between elevated scrotal temperature and reduced semen quality, but that it is uncertain whether wearing loose-fitting underwear improves fertility. [2004]
Some occupations involve exposure to hazards that can reduce fertility. Ask about the occupation of people who are concerned about their fertility, and, if necessary, direct them to appropriate advice, for example, their workplace occupational health team. [2004, amended 2026]
Ask people who are concerned about their fertility whether they are taking any prescription drugs (for example, GLP‑1 agonists, testosterone-replacement therapy or finasteride), over-the-counter products (for example, non-steroidal anti-inflammatory drugs or vaginal lubricants), or recreational drugs (for example, anabolic steroids or cannabis), and provide appropriate advice on the potential impact on fertility or pregnancy. [2004, amended 2026]
Inform people who are concerned about their fertility that the effectiveness of complementary therapies for fertility problems has not been properly evaluated, and that further research is needed before such interventions can be recommended. [2004]
For advice on folic acid supplementation, see the section on vitamin supplementation in NICE's guideline on maternal and child nutrition. [2004, amended 2026]