title: Outcome of pregnancies achieved by in vitro fertilisation techniques and diagnosed as twins at the 6 week ultrasound.
abstract: BACKGROUND
  To bring the success rate of in vitro fertilisation (IVF) procedures to an acceptable level, multiple embryos have historically been replaced. This has resulted in an 'epidemic' of multiple births. The pendulum has now swung full circle and the number of embryos transferred is now being limited. Such high numbers of IVF twins will not be produced in the future.
  
  
  OBJECTIVE
  To review retrospectively the outcome of a series of pregnancies achieved by IVF where the 6 week ultrasound showed the presence of two sacs.
  
  
  METHODS
  Retrospective study in a university IVF programme that produced 746 IVF pregnancies with twins at 6 weeks of gestation (1991-1999).
  
  
  RESULTS
  The main outcome measures were perinatal mortality, pregnancy outcome, gestation at delivery and obstetrics complications reported. Interestingly, by 20 weeks gestation, 184 (24.7%) of pregnancies spontaneously reduced to a singleton, whereas 49 (6.6%) lost both twins. Of the 513 (68.8%) viable twin pregnancies (>20 weeks), 154 (20.6%) went on to term (>37 weeks), whereas 250 (33.5%) delivered between 33 and 36 weeks gestation. The perinatal mortality per 1000 births was 6.5 over 37 weeks, 8.0 for 33-36 weeks, 41.7 for 29-32 weeks and 500 for under 28 weeks.
authors.affiliation: Monash IVF, Monash University, Richmond, Victoria, Australia. gab.Kovacs@boxhill.org.au
authors.forename: Gabor T
authors.initials: GT
authors.lastname: Kovacs
authors.forename: Sue
authors.initials: S
authors.lastname: Breheny
authors.forename: Vivien
authors.initials: V
authors.lastname: Maclachlan
authors.forename: Philip
authors.initials: P
authors.lastname: Lowe
authors.forename: Donna
authors.initials: D
authors.lastname: Howlett
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects / Q000379:methods*; D005313:Fetal Death; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007226:Infant Mortality / Q000639:trends; D007231:Infant, Newborn; D011247:Pregnancy; D011248:Pregnancy Complications / Q000000981:diagnostic imaging / Q000453:epidemiology*; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple; D012189:Retrospective Studies; D018570:Risk Assessment; D014427:Twins; D016216:Ultrasonography, Prenatal; D014739:Victoria