Impact of Male Smoking on the Couple's Infertility: Two-centre Case-control Study

About 15% of couples consult for difficulties achieving pregnancy. In about two-thirds of cases, a male component is identified, but is not always sufficient to explain infertility. In the majority of cases, the cause cannot be clearly identified and multiple abnormalities may be detected in both partners.

Many factors concerning lifestyle and environment (medications, alcohol, smoking, pollution, exposure to heat, toxins, xenobiotic oestrogens, etc.) may impact on fertility. These factors may also impact on the fertility of the children conceived, which is described as an intergenerational effect (alteration of the fertility of boys exposed to smoking in utero).

Few scientific studies with a high level of proof have been published on the impact of smoking on the couple's fertility. Gonadal functioning and the quality of gametes can be altered by these environmental factors, which may trigger a process of apoptosis or alteration of the DNA of gametes (sperm DNA fragmentation). Other modifications include DNA methylation and histone acetylation, which control gene expression and are grouped under the term epigenetic modifications. More recently, oestrogens has been shown to be involved in male reproductive function by acting on spermatogenesis, spermiogenesis and epididymal maturation. Demonstration of an active aromatase (Arom) (mRNA, protein and activity) in ejaculated human spermatozoa suggests the synthesis of small quantities of oestrogens in spermatozoa. The study of transcript profiles could provide information about the quality of spermatogenesis and/or spermiogenesis and during the first steps of embryonic development. Confocal microscopy has colocalized the aromatase on the head, midpiece and tail and can be used to assess the quality of the acrosome with anti-CD-46 monoclonal antibody. Even low concentrations of xenobiotic oestrogens can exert biological effects on certain functions of murine or human spermatozoa, accelerating capacitation and the acrosome reaction. These factors are all the more effective when they act in combination, as human gametes appear to be more sensitive to their action than murine gametes All studies conducted to date have investigated the impact of toxins either on one of the partners or in the children born to the couple. No detailed and high-level scientific study has studied both partners and the quality of their embryos.