title: Pregnancy loss rate after mid-trimester amniocentesis in twin pregnancies.
abstract: OBJECTIVE
  The purpose of this study was to estimate the attributable pregnancy loss rate of mid-trimester amniocentesis in twin pregnancies.
  
  
  METHODS
  A 16-year retrospective cohort of all twin pregnancies that underwent ultrasound evaluation at a large tertiary care medical center was followed for pregnancy outcomes. Women who underwent amniocentesis were compared with those who did not. Fetal loss was defined as loss before 24 weeks' gestation. Univariable, stratified, multivariable, and time-to-event analyses were performed.
  
  
  RESULTS
  Of 1934 twin pregnancies, 311 women elected amniocentesis. Women who elected amniocentesis were more likely to experience a pregnancy loss than those who did not (3.2% vs 1.4%; risk difference, 1.80%; 95% CI, -0.24 to 3.84%), which was significant after adjustment for advanced maternal age, chorionicity, sonographic findings, alcohol exposure, and race (adjusted odds ratio, 2.9; 95% CI, 1.2-6.9).
  
  
  CONCLUSIONS
  The attributable risk of pregnancy loss before 24 weeks' gestation after mid-trimester amniocentesis in twin pregnancies is 1 in 56 (1.8%). This information will be useful in counseling patients with twin pregnancies who are considering amniocentesis.
authors.affiliation: Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO, USA. cahilla@wustl.edu
authors.forename: Alison G
authors.initials: AG
authors.lastname: Cahill
authors.forename: George A
authors.initials: GA
authors.lastname: Macones
authors.forename: David M
authors.initials: DM
authors.lastname: Stamilio
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Dicke
authors.forename: James P
authors.initials: JP
authors.lastname: Crane
authors.forename: Anthony O
authors.initials: AO
authors.lastname: Odibo
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology* / Q000209:etiology*; D000328:Adult; D000649:Amniocentesis / Q000009:adverse effects* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015999:Multivariate Analysis; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011272:Pregnancy, Multiple; D012189:Retrospective Studies; D012307:Risk Factors; D014427:Twins