title: The impact of body mass index on assisted reproduction.
abstract: OBJECTIVE
  Obesity is a worldwide problem. The effect of obesity on the outcome of assisted reproductive techniques is quite controversial.
  
  
  RESULTS
  Although there is not an absolute consensus based on evidence, obesity may lengthen the duration of ovulation induction, increase the gonadotrophin dose, decrease the peak estradiol levels, number of mature follicles and number of oocytes retrieved, and increase the cycle cancellation rate. Moreover, obesity may have a negative impact on oocyte and embryo quality. Thus, fertilization, embryo transfer, implantation and pregnancy rates have been usually found to be low in many studies. In addition, oocyte retrieval and embryo transfer procedures can be difficult due to obesity itself. Finally, miscarriage rate is found to be high. None of the studies related with obesity and assisted reproduction has been designed as a randomized controlled trial, yet. Definition of obesity, cause of infertility, protocols used for ovulation induction, starting dose for gonadotrophins, oocyte and embryo-grading systems are not standardized among the studies. Some confounding factors, such as polycystic ovary syndrome status and age, are not taken into consideration.
  
  
  CONCLUSIONS
  Obesity has a negative impact on the outcomes of assisted reproductive techniques.
authors.affiliation: Istanbul University Cerrahpasa School of Medicine, Division of Reproductive Endocrinology, IVF Unit, Istanbul, Turkey. tamererel@superonline.com
authors.forename: Cemal
authors.initials: C
authors.lastname: Tamer Erel
authors.forename: Levent Mehmet
authors.initials: LM
authors.lastname: Senturk
mesh_terms: D015992:Body Mass Index; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000209:etiology / Q000503:physiopathology*; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D011247:Pregnancy; D027724:Reproductive Techniques, Assisted