title: The effect of ICSI, maternal age, and embryonic stage on early clinical loss rate of twin versus singleton pregnancies.
abstract: OBJECTIVE
  To compare early loss rates between twin and singleton pregnancies following ART.
  
  
  METHODS
  First-trimester sonography counted the number of embryos with positive heartbeat in women undergoing IVF/ICSI and transfer of one to three embryos. The number of lost pregnancies was calculated from a second-trimester sonogram. Loss rates of the entire pregnancy were related to maternal age <38 or > or = 38 years, IVF or ICSI, and cleavage or blastocyst stage embryo transfers (in ICSI cases).
  
  
  RESULTS
  Patients underwent IVF with (n = 672) and without (n = 189) ICSI. The overall odds of miscarrying the entire singleton pregnancy were 2.6 times that of a twin gestation (95% CI 1.5, 4.5). The disadvantage for singletons compared to twins seems more apparent in pregnancy after ICSI in the subgroup of patients <38 years (OR 2.9, 95% CI 1.5, 5.8). In this subgroup, the disadvantage conferred to singletons appeared only among days 2-3 embryo transfers (OR 3.0, 95% CI 1.3, 7.2).
  
  
  CONCLUSIONS
  A significantly lower early spontaneous loss rate of twin pregnancies seems related to ICSI followed by cleavage stage embryo transfer in patients <38 years.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, University Hospital of S. Joao, Porto, Portugal.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Matias
authors.forename: Cristiano
authors.initials: C
authors.lastname: Oliveira
authors.forename: José Teixeira
authors.initials: JT
authors.lastname: da Silva
authors.forename: Joaquina
authors.initials: J
authors.lastname: Silva
authors.forename: Alberto
authors.initials: A
authors.lastname: Barros
authors.forename: Isaac
authors.initials: I
authors.lastname: Blickstein
mesh_terms: D000328:Adult; D020964:Embryo Loss; D004624:Embryo Transfer / Q000009:adverse effects; D047108:Embryonic Development; D005260:Female; D006801:Humans; D008423:Maternal Age; D016017:Odds Ratio; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000009:adverse effects*; D014427:Twins; D016216:Ultrasonography, Prenatal