Sylvia ChebetFor people trying to have a baby, quitting smoking may seem like an obvious place to start. But what if you do not smoke yourself?
The World Health Organization (WHO) is warning that second-hand tobacco smoke may also affect fertility, meaning reproductive risks are not limited to people who use tobacco.
“Not smoking yourself does not necessarily mean you are free from tobacco smoke exposure,” warns Dr William K Maina of the Tobacco Control Programme at the WHO Regional Office for Africa.
Second-hand smoke comes from the burning end of a tobacco product as well as smoke exhaled by a smoker. Non-smokers can inhale these toxic substances involuntarily.
According to the WHO review, women who do not smoke but are exposed to second-hand smoke have an estimated 1.2-times higher risk of infertility. Studies also suggest they may have a lower chance of conceiving in any given month.
But there is no clearly defined level of exposure considered safe.
“The evidence ... does not establish a specific threshold or number of cigarettes, hours or days of exposure below which there is no reproductive risk,” Maina says.
That makes the environments people spend time in particularly important.
WHO advises avoiding tobacco smoke wherever possible, especially in enclosed spaces such as homes, workplaces and vehicles. For couples planning a pregnancy, Maina says helping a smoking partner quit can protect both people from continued exposure.
The warning comes alongside broader evidence linking smoking directly to infertility.
A systematic review of studies conducted between 2000 and 2026 found that women who currently smoke had a 40% higher risk of infertility than non-smokers. The review also found that women who had smoked in the past but no longer did had about a 25% lower risk of infertility than women who continued to smoke.
For men, the impact can include poorer semen quality and sexual dysfunction. A review of 44 studies involving more than 60,000 men found associations between smoking and erectile dysfunction, ejaculation problems, poor sperm motility and abnormal sperm shape.
Smoking can also affect couples already undergoing fertility treatment. A meta-analysis of 21 studies found that smokers had about 44% lower odds of pregnancy and 46% lower odds of a live birth following assisted reproduction.
And newer products are not necessarily a safe alternative.
Evidence on e-cigarettes and waterpipes remains limited, but emerging research suggests potential reproductive risks. One study of more than 4,500 women found that ever-use of e-cigarettes was associated with about a 20% reduction in fecundability, or the probability of conceiving during a menstrual cycle.
For Maina, the message is straightforward: tobacco and fertility should be considered a shared reproductive-health issue.
“The most important message is: stop using tobacco as early as possible, ideally before trying to conceive.”
And for non-smokers, avoiding exposure matters too.
Not lighting the cigarette yourself does not mean you are necessarily avoiding its effects.
