title: Association of number of retrieved oocytes with live birth rate and birth weight: an analysis of 231,815 cycles of in vitro fertilization.
abstract: OBJECTIVE
  To determine if number of retrieved oocytes correlates with live birth rate and incidence of low birth weight (LBW).
  
  
  METHODS
  Retrospective cohort.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Women undergoing fresh embryo transfer with the use of either autologous (n = 194,627) or donor (n = 37,188) oocytes whose cycles were reported to the Society for Assisted Reproductive Technology in the years 2004-2010.
  
  
  METHODS
  None.
  
  
  METHODS
  Live birth rate, birth weight, birth weight z-score, LBW.
  
  
  RESULTS
  For both autologous and donor oocyte cycles, increasing number of retrieved oocytes paralleled live birth rate and embryos available for cryopreservation in most analyses, with all models adjusted for age and previous births. For cycles achieving singleton pregnancy with the use of autologous oocytes via transfer of two embryos, a higher number of retrieved oocytes was associated with lower mean birth weight, lower birth weight z-score, and greater incidence of LBW. In contrast, for cycles using donor oocytes, there was no association of number of retrieved oocytes with measures of birth weight.
  
  
  CONCLUSIONS
  A higher number of retrieved oocytes was associated with an increased incidence of LBW in autologous singleton pregnancies resulting from transfer of two embryos, but not in donor oocyte cycles. Although the effect of high oocyte number on the incidence of LBW in autologous cycles was of modest magnitude, further study is warranted to determine if a subgroup of women may be particularly vulnerable.
authors: Department of Obstetrics and Gynecology, Stanford University School of Medicine, Palo Alto, California. Electronic address: vlbaker@stanford.edu.
authors: Valerie L
authors: VL
authors: Baker
authors: Department of Biostatistics, University of Michigan, Ann Arbor, Michigan.
authors: Morton B
authors: MB
authors: Brown
authors: Department of Obstetrics, Gynecology, and Reproductive Biology, College of Human Medicine, Michigan State University, East Lansing, Michigan.
authors: Barbara
authors: B
authors: Luke
authors: Department of Physiology and Functional Genomics and Department of Obstetrics and Gynecology, University of Florida College of Medicine, Gainesville, Florida.
authors: Kirk P
authors: KP
authors: Conrad
mesh_terms: D001724:Birth Weight; D002452:Cell Count; D015925:Cryopreservation / Q000706:statistics & numerical data; D005260:Female; D005307:Fertilization in Vitro / Q000706:statistics & numerical data*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D018587:Oocyte Donation / Q000706:statistics & numerical data; D054315:Oocyte Retrieval / Q000706:statistics & numerical data*; D009865:Oocytes / Q000166:cytology*; D011247:Pregnancy; D018873:Pregnancy Rate; D047928:Premature Birth / Q000453:epidemiology; D012189:Retrospective Studies
keywords: In vitro fertilization; birth weight; live birth rate; low birth weight; oocyte number; z-score
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