Human Reproduction Keynote lecture 2016, by Allan Pacey, Sheffield, UK
The annual Human Reproduction keynote lecture is an honorary lecture given by the author of the most downloaded recent original paper from the three ESHRE journals. Altmetrics (lay press reports, tweets, Facebook likes) are also taken into account. This year, a paper on lifestyle effects on sperm quality dominated the field.
Popular belief has it that your lifestyle can affect your sperm. The scientific evidence for this is weak however: it is derived from small, underpowered studies, often without adequate comparison groups. Allan Pacey’s research group from Sheffield and Manchester addressed the question, “Are common lifestyle factors associated with poor sperm morphology?” in over 300 cases and more than 1500 referents. Cases had poor (computer assessed) sperm morphology (<4% normal forms based on 200 sperm cells assessed). Exposures consisted of self-reported exposures to alcohol, tobacco, recreational drugs as well as occupational and other factors. Mobile phone use was not taken into account.
The investigators found a doubling of the risk for poor sperm shape and size if sample production occurred in summer, and also a doubling by the use of cannabis in the three months prior to sample collection in men aged ≤30 years. Men who produced a sample after abstinence (of six days) were 36% less likely to be a case. No significant association was found with body mass index (BMI), type of underwear, smoking or alcohol consumption or having a history of mumps.
This suggests that an individual’s lifestyle has little impact on his sperm morphology and – indirectly – that delaying assisted conception to change lifestyle is unlikely to enhance pregnancy chances. So, the findings are quite reassuring. Producing a sample in summer and using cannabis are associated with sperm shape and size abnormalities, but BMI, underwear, smoking and drinking alcohol are not. Infertile men with moderate alcohol consumption or a taste for tight-fitting underwear need not be concerned any longer. Says Pacey.
Hans Evers, Editor in Chief of Human Reproduction