September 8, 2010

expert reaction to research into smoking and sperm, to be published in Human Reproduction

Two papers published in the journal Human Reproduction examine the evidence around the effect of smoking on sperm production and fertility.

Dr Allan Pacey, Senior Lecturer in Andrology, University of Sheffield, said:

“These two studies provide further proof that the smoking of cigarettes is bad for the reproductive system of men and women.

“The first, by Mamsen and colleagues, elegantly provides further support for the theory that the most critical time which determines how fertile an adult will be is actually in the time before they were born. This is a hard concept to grasp, but given the knowledge that women are born with the entire supply of eggs, and men are born with the number of sperm producing cells, they will ever have means that what mothers are exposed to during pregnancy can be vitally important for the reproductive health of their children when they reach adulthood.

“The second study by Hammadeh and colleagues, examined the levels of two forms of the same protein ‘protamine’ that are present in sperm and play a crucial role in making sure that sperm DNA is tightly packaged, and therefore protected, during the time when sperm are waiting to be ejaculated or making their way to the egg inside a woman’s body. We already suspect that sperm with damaged DNA are not as effective as they should be, and in some people damaged sperm DNA may contribute to their infertility or increase the risk of miscarriage in their partners. This research adds some further details to this story and explains how this sperm DNA-vulnerability might occur in men who are exposed to cigarette smoke.

“Clearly couples trying to conceive should not smoke and should avoid exposure to cigarette smoke. To make sure sperm are healthy, this needs to be sustained as it takes about three months to produce a cohort of sperm: stopping smoking on Friday does not mean healthy sperm by Monday! Furthermore, once a woman is pregnant, is it vitally important that she does not smoke and that the baby is not exposed to the harmful chemicals contained in cigarette smoke whilst it is developing. It breaks my heart to see pregnant women having a crafty cigarette outside the Maternity hospital in Sheffield where I work. That is not the best start in life for any baby. But equally we need to recognise that for some people stopping smoking is hard and we need to support them to give up.”

* Both papers were published in Human Reproduction on Wednesday 8 September 2010. 1. Cigarette smoking during early pregnancy reduces the number of embryonic germ and somatic cells, Mamsen et al. 2. Protamine contents and P1/P2 ratio in human spermatozoa from smokers and non-smokers, Hammadeh et al.