Increased body mass index negatively impacts blastocyst formation rate in normal responders undergoing in vitro fertilization

J Assist Reprod Genet. 2015 Sep;32(9):1299-304. doi: 10.1007/s10815-015-0515-1. Epub 2015 Jun 25.


Purpose: 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).

Conclusion: 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.

Keywords: Blastocyst; Embryo quality; IVF outcome; Metabolic dysfunction; Obesity.

MeSH terms

  • Adult
  • Blastocyst / cytology*
  • Blastocyst / physiology
  • Body Mass Index*
  • Body Weight
  • Case-Control Studies
  • Embryo Transfer
  • Embryonic Development
  • Female
  • Fertilization / physiology*
  • Fertilization in Vitro / methods*
  • Follow-Up Studies
  • Humans
  • Obesity / physiopathology*
  • Oocytes / cytology*
  • Oocytes / physiology
  • Pregnancy
  • Pregnancy Rate
  • Prognosis
  • Retrospective Studies