By Sally Robertson, medwireNews Reporter
Male body mass index (BMI) influences pregnancy outcome in couples undergoing in vitro fertilization (IVF) through its effect on embryo quality rather than on sperm parameters, report researchers.
The quality of the transferred embryos influenced implantation rates, something that was directly reflected in IVF outcomes in the study, report Georgios Anifandis (University of Thessaly, Larissa, Greece) and colleagues in Andrology.
In a retrospective analysis of 301 couples undergoing IVF, there was no correlation found overall between BMI and semen volume or concentration.
However, on stratifying the couples by BMI, the team found that in cases where both the male and female were overweight or obese, as defined by a BMI of more than 25 kg/m2, the cumulative embryo score was significantly lower than when both were lean or normal weight (normal weight group, BMI ≤25 kg/m2) or when only the females were overweight or obese but the males were not (overweight/obese female group).
Among couples where the female was lean or normal weight but the male was overweight or obese (overweight/obese male group), the embryo quality was again significantly lower than in the normal weight group and the obese female group.
In addition, "it seems that the quality of the embryos produced by each group played a crucial role in the implantation rate," say Anifandis and colleagues, who found that the implantation rate was significantly higher among the normal weight and obese female groups than in the obese group or obese male group.
In addition, pregnancy rates were significantly higher in the normal weight group and obese female group than in the obese group and obese male group.
The team says previous research has shown a link between increased BMI in men and abnormalities in levels of almost all of the reproductive hormones.
It seems that the BMI of men via the alteration in hormonal parameters influences the sperm DNA integrity to such a degree that this alteration has a direct impact on embryo quality, say Anifandis et al.
However, "whether the BMI of men or the deviation of hormonal parameters influence embryo quality remains to be further clarified," they conclude.
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