title: Contribution of twin-to-twin transfusion syndrome to preterm birth among monochorionic biamniotic and bichorionic biamniotic twin pregnancies.
abstract: To determine the contribution of twin-to-twin transfusion syndrome (TTTS) to preterm birth (PTB) at <37 weeks of gestation among Japanese twin pregnancies.
  
  
  
  An observational study using 3241 MC-BA (monochorionic biamniotic) and 6581 BC (bichorionic biamniotic) twin pregnancies. We focused on TTTS, preterm premature rupture of membranes (PPROM), pregnancy-induced hypertension (PIH), and fetal sex as possible causes of PTB.
  
  
  
  PTB was more common in MC-BA than in BC twin pregnancies (66.9% vs. 57.6%, P<0.0001) whereas PTB after PPROM (8.0% vs. 10.0%) and PIH (5.7% vs. 5.9%) was not. PTB after TTTS occurred in 7.3% of women with MC-BA twins. PTB was significantly more common for male-male pairs than for female-female pairs among both MC-BA (69.2% vs. 64.7%) and BC (59.6% vs. 56.3%) twins.
  
  
  
  The elevated risk of PTB among MC-BA twins could be explained by the occurrence of TTTS.
authors.affiliation: Department of Obstetrics and Gynecology, Hokkaido University Graduate School of Medicine, Sapporo, Japan. mmamoru@med.hokudai.ac.jp
authors.forename: Mamoru
authors.initials: M
authors.lastname: Morikawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamada
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamada
authors.forename: Shoji
authors.initials: S
authors.lastname: Sato
authors.forename: Hisanori
authors.initials: H
authors.lastname: Minakami
mesh_terms: D000328:Adult; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000209:etiology; D005330:Fetofetal Transfusion / Q000150:complications*; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000209:etiology; D007231:Infant, Newborn; D007234:Infant, Premature; D007564:Japan; D008297:Male; D011247:Pregnancy; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000209:etiology*; D012307:Risk Factors; D012737:Sex Factors; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic