title: Increased body mass index negatively impacts blastocyst formation rate in normal responders undergoing in vitro fertilization.
abstract: OBJECTIVE
  The aim of this study is to investigate the effect of female BMI and metabolic dysfunction on blastocyst formation rate.
  
  
  METHODS
  This was a retrospective cohort study that was performed in an academic center for reproductive medicine. Patients who were normal weight, overweight with metabolic dysfunction, or obese who had ≥6 oocytes retrieved in a fresh IVF cycle were included in the study. The blastocyst formation rate was calculated from the number of ≥5 cell embryos on day 3 observed in culture until day 5 or day 6. Only good quality blastocysts were included in the calculation as defined by a morphologic grade of 3BB or better.
  
  
  RESULTS
  The blastocyst formation rate was significantly better in the normal-weight controls versus overweight/obese patients (57.2 versus 43.6 %, p < 0.007). There was no difference in blastocyst formation between the patients with a BMI 25-29.9 kg/m(2) with metabolic dysfunction and those with a BMI ≥30 kg/m(2).
  
  
  CONCLUSIONS
  The maternal metabolic environment has a significant impact on embryo quality as measured by blastocyst formation. A decreased blastocyst formation rate is likely a significant contributor to poorer reproductive outcomes in overweight and obese women with infertility.
authors.affiliation: Obstetrics and Gynecology-Reproductive Endocrinology and Infertility, Stanford Hospital and Clinics, 900 Welch Rd Ste 350 MC 5800, Palo Alto, CA, 94304, USA. icomstoc@stanford.edu.
authors.forename: Ioanna A
authors.initials: IA
authors.lastname: Comstock
authors.affiliation: Medical Endocrinology, Stanford Hospital and Clinics, 300 Pasteur Dr S025 MC 5103, Palo Alto, CA, 94304, USA. sunhkim@stanford.edu.
authors.forename: Sun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Obstetrics and Gynecology-Reproductive Endocrinology and Infertility, Stanford Hospital and Clinics, 900 Welch Rd Ste 350 MC 5800, Palo Alto, CA, 94304, USA. behr@stanford.edu.
authors.forename: Barry
authors.initials: B
authors.lastname: Behr
authors.affiliation: Obstetrics and Gynecology-Reproductive Endocrinology and Infertility, Stanford Hospital and Clinics, 900 Welch Rd Ste 350 MC 5800, Palo Alto, CA, 94304, USA. rlathi@stanford.edu.
authors.forename: Ruth B
authors.initials: RB
authors.lastname: Lathi
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000166:cytology* / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight; D016022:Case-Control Studies; D004624:Embryo Transfer; D047108:Embryonic Development; D005260:Female; D005306:Fertilization / Q000502:physiology*; D005307:Fertilization in Vitro / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D009765:Obesity / Q000503:physiopathology*; D009865:Oocytes / Q000166:cytology* / Q000502:physiology; D011247:Pregnancy; D018873:Pregnancy Rate; D011379:Prognosis; D012189:Retrospective Studies
keywords: Blastocyst; Embryo quality; IVF outcome; Metabolic dysfunction; Obesity