Thanos Papathanasiou: The Effect of Male Smoking on IVF Success

Thanos Papathanasiou, CEO and Medical Director at Bourn Hall Fertility Clinic UK, shared a post on LinkedIn about a paper by Gideon Verwoerd et al. published in Fertility and Sterility:

“I am pleased to share our recent publication in Fertility and Sterility, examining the effect of male smoking on IVF success.

There has been considerable research on smoking and fertility over the years, but the evidence specifically linking male smoking to IVF outcomes has remained surprisingly inconsistent.

I think part of the problem lies in how these studies have been designed. Previous research has often relied on relatively small or retrospective datasets, sometimes without clearly separating the effects of male and female smoking. Smokers have frequently been treated as a single group, regardless of how much they smoke.

Perhaps more importantly, many studies have focused on pregnancy rates following individual embryo transfers, rather than the overall chance of having a baby from an IVF treatment.

These may appear to be methodological details, but they can substantially influence the findings and, ultimately, the conclusions we draw.

In our study, we tried to address these limitations. We prospectively followed more than 1,300 couples, comparing those where neither partner smoked with those where only the male partner smoked. We examined cumulative live birth following one egg collection, including subsequent frozen embryo transfers, distinguished between different smoking intensities, and adjusted for several important confounding factors.

Our findings showed that couples where the man smoked 20 or more cigarettes daily had a 19% lower relative chance of achieving a live birth. The association was less pronounced among lighter smokers and was not statistically significant for cumulative live birth.

My own involvement in this research was primarily methodological, something I particularly enjoy. Observational studies can be challenging because the data may tell different stories depending on how we define our outcomes, select our comparison groups, account for confounding factors and interpret subgroup findings.

I have always felt that getting these decisions right from the beginning is just as important as the statistical analysis itself. Otherwise, even a large study can produce findings that are difficult to interpret or potentially misleading.
Of course, our prospective study remains observational, with its own limitations, and cannot establish causation; but then again, we can’t ethically randomise patients into smoking and non-smoking!

Even so, I believe it adds useful evidence to an area where previous findings have been inconsistent and where better information can help us counsel couples undergoing IVF.

Many thanks to Gideon Verwoerd, Robert West, Jinfeng Cai and Yunyan Chen for this very enjoyable collaboration. Gideon, you did it!”

Title: The Effect of Male Partner Smoking on Cumulative Live Birth after In vitro Fertilization (IVF): a Large Prospective Cohort Study

Authors: Gideon Verwoerd, Robert West, Jinfeng Cai, Yunyan Chen, Athanasios Papathanasiou

You can read the Full Article in Fertility and Sterility.

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