A new publication by the World Health Organisation (WHO) has warned that smoking may reduce the chances of conceiving and lower the success rates of some fertility treatments.

The publication said tobacco use is associated with infertility in women, while in men it can damage sperm quality and sexual function. It also warned that exposure to second-hand smoke may affect fertility, meaning people who do not smoke could also face reproductive risks.

Globally, about one in six people of reproductive age experiences infertility at some point in their lifetime. WHO defines infertility as the failure to achieve pregnancy after 12 months or more of regular unprotected sexual intercourse.

The publication cited decades of evidence linking smoking with poor reproductive health. A systematic review of studies conducted between 2000 and 2026 found that women who currently smoke tobacco have a 40 per cent higher risk of infertility than non-smokers.

It also noted that women who previously smoked but no longer do had a 25 per cent lower risk of infertility compared with those who continued smoking, suggesting that quitting could significantly improve reproductive health.

WHO stressed that infertility is not solely a women’s health problem. A review of 44 studies involving more than 60,000 men found that smoking was associated with reproductive dysfunction, including semen abnormalities and sexual problems.

According to the publication, male smokers were more likely to experience erectile dysfunction, ejaculation problems and sperm-related abnormalities, including absence of sperm in semen, poor sperm motility and abnormal sperm shape.

For people undergoing fertility treatment, smoking may also reduce the likelihood of success. WHO cited research from 21 studies linking cigarette smoking with fewer pregnancies and live births following assisted reproductive procedures such as in-vitro fertilisation (IVF). The findings suggested that smoking could roughly halve the chances of successful outcomes.

The organisation further warned that second-hand smoke exposure may increase the risk of infertility. Women exposed to tobacco smoke from others may have a higher risk of infertility and a lower chance of conceiving in each menstrual cycle.

While evidence on newer products, including e-cigarettes, waterpipes and smokeless tobacco, is still emerging, WHO said the strongest evidence currently concerns cigarette smoking. It cautioned, however, that other tobacco and nicotine products could also pose fertility risks and require further research.

WHO urged healthcare providers to inform individuals and couples planning pregnancy about the reproductive risks of tobacco use and provide evidence-based support to help them quit.

It also recommended that brief advice on quitting should be routinely offered to all tobacco users across healthcare settings.

WHO said infertility affects millions of people worldwide and can have significant consequences for individuals, families and communities and may result from male, female or unexplained factors.