title: Which one has a better obstetric and perinatal outcome in singleton pregnancy, IVF/ICSI or FET?: a systematic review and meta-analysis.
abstract: BACKGROUND
  The present study aims to compare which one has a better obstetric and perinatal outcome in singleton pregnancy, frozen embryo transfer (FET) or. in vitro fertilization treatment/intracytoplasmic sperm injection (IVF/ICSI)?
  
  
  METHODS
  MEDLINE, Google Scholar and the Cochrane Library were searched for the obstetric and perinatal outcomes in singleton pregnancy after assisted reproductive technology (ART) from inception until July 2016. Clinical trials, which compared obstetric/perinatal outcomes in singleton pregnancy after FET and IVF/ICSI-ET, were included. The primary outcome was low birth weight, preterm birth, perinatal mortality, still birth, and cesarean section.
  
  
  RESULTS
  Thirteen cohort studies with 126,911 women were included, of which 12, 11, 6, 6, 5 studies were used to analyze low birth weight, preterm birth, perinatal mortality, still birth, and cesarean section, respectively. IVF/ICSI is associated with a high risk of preterm birth (OR = 1.14, 95 % CI: 1.02, 1.28) and low birth rate (OR = 1.48, 95 % CI: 1.37, 1.60). There was no significant difference in the risk of the still birth (OR = 1.01, 95 % CI: 0.76, 1.35) and perinatal mortality (OR = 1.11, 95 % CI: 0.85, 1.46) between FET and IVF/ICSI. Singleton pregnancy after FET was associated with higher cesarean section rate compared with IVF/ICSI (OR = 0.85, 95 % CI: 0.80, 0.91).
  
  
  CONCLUSIONS
  Singleton pregnancy after FET seems to have a better perinatal outcome compared with that after IVF/ICSI. Further randomized controlled trials which adjust for a variety of meaningful confounders are needed in order to draw sound conclusions.
authors: Department of Reproductive Medicine, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha City, 410008, Hunan Province, People's Republic of China.
authors: J
authors: J
authors: Zhao
authors: Department of Reproductive Medicine, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha City, 410008, Hunan Province, People's Republic of China.
authors: B
authors: B
authors: Xu
authors: Department of Reproductive Medicine, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha City, 410008, Hunan Province, People's Republic of China.
authors: Q
authors: Q
authors: Zhang
authors: Department of Reproductive Medicine, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha City, 410008, Hunan Province, People's Republic of China. LYP7798@126.com.
authors: Y P
authors: YP
authors: Li
mesh_terms: D002585:Cesarean Section / Q000639:trends; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000639:trends*; D004624:Embryo Transfer / Q000639:trends*; D005260:Female; D005307:Fertilization in Vitro / Q000639:trends*; D006801:Humans; D007230:Infant, Low Birth Weight / Q000502:physiology; D007231:Infant, Newborn; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D047928:Premature Birth / Q000175:diagnosis / Q000453:epidemiology; D020554:Sperm Injections, Intracytoplasmic / Q000639:trends*
keywords: Frozen embryo transfer (FET); In vitro fertilization (IVF); Intracytoplasmic sperm injection (ICSI); Obstetric outcomes; Perinatal outcomes