Obesity and assisted reproduction.

The World Health Organization defines obesity as an abnormal or excessive accumulation of fat that is harmful to health. Obesity and overweight have a negative effect not only on general health, but also on reproductive health. Obesity is associated with reduced fertility, more frequent pregnancy losses and other pregnancy complications. Due to an obesity pandemic, an increasing proportion of women seeking medical help for infertility will be overweight or obese. Obesity is involved in the pathogenesis of polycystic ovary syndrome (PCOS), approximately 40-70% of PCOS patients are overweight or obese. The risk of miscarriage is increased in obese women who become pregnant after in vitro fertilisation, regardless of whether their own oocytes or donated oocytes are used. In men, the link between obesity and reduced fertility is less well-studied than in women. Mechanisms by which obesity may affect spermatogenesis include thermal effects, hyperestrogenism, hypogonadotropic hypogonadism, diabetes mellitus, sexual dysfunction, and sperm epigenetic disorders. Obesity in both women and men negatively affects the results of assisted reproduction. Overweight or obese women should be informed about the overall health and obstetric risks and about the lower success rate of infertility treatment with assisted reproduction methods.