title: Moderate ovarian stimulation does not increase the incidence of human embryo chromosomal abnormalities in in vitro fertilization cycles.
abstract: BACKGROUND
  A high chromosomal abnormalities rate has been observed in human embryos derived from in vitro fertilization (IVF) treatments. The real incidence in natural cycles has been poorly studied, so whether this frequency may be induced by external factors, such as use of gonadotropins for ovarian stimulation, remains unknown.
  
  
  METHODS
  We conducted a prospective cohort study in a University-affiliated private infertility clinic with a comparison between unstimulated and stimulated ovarian cycles in the same women. Preimplantation genetic screening by fluorescence in situ hybridization was performed in all viable d 3 embryos.
  
  
  OBJECTIVE
  The primary objective was to compare the incidence of embryo chromosomal abnormalities in an unstimulated cycle and in an ulterior moderate ovarian stimulated cycle. Secondary outcome measures were embryo quality, blastocyst rate of biopsied embryos, number of normal blastocysts per donor, type of chromosomal abnormalities, and clinical outcome.
  
  
  RESULTS
  One hundred eighty-five oocyte donors were initially recruited for the unstimulated cycle, and preimplantation genetic screening could be performed in 51 of them, showing 35.3% of embryo chromosomal abnormalities. Forty-six of them later completed a stimulated cycle. The sperm donor sample was the same for both cycles. The proportion of embryos displaying abnormalities in the unstimulated cycle was 34.8% (16 of 46), whereas it was 40.6% (123 of 303) in the stimulated cycle with risk difference=5.8 [95% confidence interval (CI)=-20.6-9.0], and relative risk=1.17 (95% CI=0.77-1.77) (P=0.45). When an intrasubject comparison was made, the abnormalities rate was 34.8% (95% CI=20.5-49.1) in the unstimulated cycle and 38.2% (95% CI=30.5-45.8) in the stimulated cycle [risk difference=3.4 (95% CI=-17.9-11.2); P=0.64]. No differences were observed for embryo quality and type of chromosomal abnormalities.
  
  
  CONCLUSIONS
  Moderate ovarian stimulation in young normo-ovulatory women does not significantly increase the embryo aneuploidies rate in in vitro fertilization-derived human embryos as compared with an unstimulated cycle. Whether these results can be extrapolated to infertile patients is still unknown.
authors.affiliation: Department of Human Reproduction, Instituto Valenciano de Infertilidad, University of Valencia, Plaza de la Policía Local 3, 46015 Valencia, Spain. elena.labarta@ivi.es
authors.forename: Elena
authors.initials: E
authors.lastname: Labarta
authors.forename: Ernesto
authors.initials: E
authors.lastname: Bosch
authors.forename: Pilar
authors.initials: P
authors.lastname: Alamá
authors.forename: Carmen
authors.initials: C
authors.lastname: Rubio
authors.forename: Lorena
authors.initials: L
authors.lastname: Rodrigo
authors.forename: Antonio
authors.initials: A
authors.lastname: Pellicer
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000166:cytology*; D002869:Chromosome Aberrations / Q000139:chemically induced / Q000706:statistics & numerical data*; D004305:Dose-Response Relationship, Drug; D047108:Embryonic Development / Q000187:drug effects / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D005498:Follicular Phase / Q000187:drug effects / Q000502:physiology; D006062:Gonadotropins / Q000008:administration & dosage / Q000009:adverse effects; D006801:Humans; D015994:Incidence; D007247:Infertility, Female / Q000628:therapy*; D010062:Ovulation Induction / Q000009:adverse effects / Q000379:methods*; D011247:Pregnancy; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D006062:Gonadotropins