title: BMI-related metabolic composition of the follicular fluid of women undergoing assisted reproductive treatment and the consequences for oocyte and embryo quality.
abstract: OBJECTIVE
  Is the metabolic composition of the follicular fluid of women undergoing assisted reproductive treatment (ART) related to serum composition and BMI and is it associated with oocyte and embryo quality?
  
  
  CONCLUSIONS
  We showed that metabolic alterations in the serum are reflected in the follicular fluid and that some of these alterations may affect oocyte quality, irrespective of BMI.
  
  
  BACKGROUND
  Many studies have focused on the effect of metabolic disorders, such as obesity and type 2 diabetes, on assisted reproduction outcomes. There are, however, only few studies focusing on the importance of the correlation between serum and follicular fluid compositions and the composition of the follicular fluid as the oocyte's micro-environment, affecting its development and subsequent embryo quality.
  
  
  METHODS
  In this prospective cohort study, patient information, fertility treatment outcome data, follicular fluid and serum were obtained from women undergoing ART. Patients were categorized according to their BMI (kg/m(2)) as normal (n = 60), overweight (n = 26) or obese (n = 20). Serum and follicular fluid samples were analyzed for urea, total protein, albumin, cholesterol, high-density lipoprotein cholesterol, triglycerides, non-esterified fatty acids, apolipoprotein A1, apolipoprotein B, glucose, lactate, C-reactive protein, insulin-like growth factor -1 (IGF-1), IGF-binding protein 3 (only in follicular fluid), free carnitine and total carnitine. Metabolite concentrations in serum and follicular fluid samples were correlated and were associated with BMI and fertility treatment outcome.
  
  
  RESULTS
  Most serum metabolite differences between patients were reflected in the follicular fluid (P < 0.05). Follicular fluid apolipoprotein A1 and follicular fluid total protein concentrations negatively affected oocyte quality parameters (P < 0.05). However, overall BMI-related associations were poor.
  
  
  CONCLUSIONS
  In this study, we included every patient willing to participate. Within this cohort, women with a BMI transcending 35 kg/m(2) were scarce (n = 2), because extremely overweight women are mostly advised to lose weight before starting ART. Furthermore, the number of patients in each BMI group was different, possibly masking associations between the metabolic composition of serum and follicular fluid and oocyte quality parameters.
  
  
  CONCLUSIONS
  There were significant associations indicating that metabolic changes in the serum are reflected in the follicular fluid, potentially affecting oocyte quality, irrespective of the patient's BMI. For ethical reasons, this study only focused on women already in need of artificial reproductive treatment. From a metabolic point of view, we consider this cohort as a representative sample of all women of reproductive age.
  
  
  BACKGROUND
  This study was funded by the special research fund, university of Antwerp (BOF UA). None of the authors has any conflict of interest to declare.
authors.affiliation: Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Belgium. sara.valckx@ua.ac.be
authors.forename: S D M
authors.initials: SD
authors.lastname: Valckx
authors.forename: I
authors.initials: I
authors.lastname: De Pauw
authors.forename: D
authors.initials: D
authors.lastname: De Neubourg
authors.forename: I
authors.initials: I
authors.lastname: Inion
authors.forename: M
authors.initials: M
authors.lastname: Berth
authors.forename: E
authors.initials: E
authors.lastname: Fransen
authors.forename: P E J
authors.initials: PE
authors.lastname: Bols
authors.forename: J L M R
authors.initials: JL
authors.lastname: Leroy
mesh_terms: D000328:Adult; D015992:Body Mass Index; D004622:Embryo, Mammalian; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007246:Infertility / Q000097:blood / Q000378:metabolism / Q000628:therapy; D050356:Lipid Metabolism; D009765:Obesity / Q000097:blood / Q000150:complications*; D054315:Oocyte Retrieval; D009865:Oocytes / Q000502:physiology*; D050177:Overweight / Q000097:blood / Q000150:complications* / Q000378:metabolism; D011446:Prospective Studies; D027724:Reproductive Techniques, Assisted; D016896:Treatment Outcome