title: Outcomes of singleton births after blastocyst versus nonblastocyst transfer in assisted reproductive technology.
abstract: OBJECTIVE
  To compare obstetric and perinatal outcomes of singleton births after assisted reproductive technology (ART) with blastocyst transfer (days 5 to 6) versus nonblastocyst transfer (days 2 to 4).
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Monash IVF.
  
  
  METHODS
  4,202 women who conceived using in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) between 2004 and 2009.
  
  
  METHODS
  Records analysis of fresh and frozen-thawed embryo transfers resulting in singleton births of at least 20 weeks' gestation.
  
  
  METHODS
  Perinatal outcomes: preterm birth, low birthweight, very low birthweight, small for gestational age, large for gestational age, preeclampsia, antepartum hemorrhage, placental abruption, placenta previa, and postpartum hemorrhage; and covariates: maternal age, year of birth of the baby, private health insurance status, maternal body mass index, smoking status, parity, gender of baby, and variations in treatment procedures.
  
  
  RESULTS
  Multivariate analysis found no statistically significant difference between transfers on days 5 and 6 and days 2 and 4 for all maternal and perinatal outcomes. There were modest increases in the adjusted odds ratios for preeclampsia (adjusted odds ratio 1.72, 99% confidence interval 0.93-3.20) and placenta previa (1.65, 0.92-2.98).
  
  
  CONCLUSIONS
  Obstetric and perinatal outcomes after blastocyst transfer on days 5 to 6 are similar when compared with embryo cleavage-stage transfers on days 2 to 4.
authors.affiliation: Monash University, Clayton, Victoria, Australia.
authors.forename: Dhanushi
authors.initials: D
authors.lastname: Fernando
authors.forename: Jane L
authors.initials: JL
authors.lastname: Halliday
authors.forename: Susan
authors.initials: S
authors.lastname: Breheny
authors.forename: David Lindsay
authors.initials: DL
authors.lastname: Healy
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D002970:Cleavage Stage, Ovum; D046149:Embryo Culture Techniques; D004624:Embryo Transfer / Q000009:adverse effects*; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects; D006801:Humans; D007231:Infant, Newborn; D050498:Live Birth; D016015:Logistic Models; D015999:Multivariate Analysis; D016017:Odds Ratio; D011247:Pregnancy; D011248:Pregnancy Complications / Q000209:etiology*; D027724:Reproductive Techniques, Assisted / Q000009:adverse effects*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020554:Sperm Injections, Intracytoplasmic / Q000009:adverse effects; D013997:Time Factors; D016896:Treatment Outcome; D014739:Victoria