Chinese men who smoke are twice as likely to have abnormal semen than those who do not, according to a recent study.
The claim is based on research by the China Sexology Association, China Andrology Association and Peking University Third Hospital, details of which were published on Thursday.
In the study of 4,364 men, carried out at 25 medical institutes across China, 32% of those who smoked were found to have abnormal semen, while the figure was 16.6% for those who did not.
According to the World Health Organisation, the term “abnormal semen” can be used to describe a lower than normal sperm count, poor sperm vitality, or a higher than normal number of irregularly shaped sperm.
The study’s compilers said 51% of the participants were smokers, of whom 40% smoked more than 10 cigarettes a day. About 60% of the smokers had been doing so for at least five years, it said.
“Smoking has a negative impact on fertility, as the nicotine in cigarettes harms sperm, eggs and embryos,” said Jiang Hui, deputy director of the China Sexology Association, a non-profit organisation.
Of the men who took part in the study, 43% said they were aware of the risks smoking posed to sperm quality and fertility, while almost all of them said they knew smoking was harmful to their overall health.
The Chinese study added weight to previous research into the subject.
In 2016, researchers at the American Centre for Reproductive Medicine, said that of the 6,000 men in their study, those who were regularly exposed to cigarette smoke had notably fewer sperm per ejaculation, fewer mobile sperm and more irregularly shaped sperm. Their findings were published in the medical journal European Urology.
According to a 2014 report by the WHO, China has about 300 million smokers -- about a third of the adult population -- and more than half of all Chinese men smoke.