title: Gender prevalence in twin-twin transfusion syndrome.
abstract: BACKGROUND
  This study aimed to determine the gender prevalence of fetuses complicated with twin-twin transfusion syndrome (TTTS).
  
  
  METHODS
  All cases of TTTS corresponded with the following major criteria: a single placenta, monochorion, the same gender, and a combination of polyhydramnios-oligohydramnios. At least one of three minor criteria were required for the establishment of TTTS, including a stuck twin, a birth weight discordance exceeding 20%, and hemoglobin difference > 5 g/dl.
  
  
  RESULTS
  Fifty-six twin pregnancies met the above criteria, of which 33 (58.9%) twin pairs were female. The female tendency existed, but there was a non-significant difference. Mean gestational age at diagnosis was 20.2 +/- 3.2 weeks. The birth weight discordance exceeding 20% was present in 50 of 56 (89.3%), and mean growth discordance was 32% +/- 8%. A stuck twin was noted in 37 of 56 cases (66.1%). The mortality of fetuses or neonates was 34.8% (39/112), including 8 (7.1%) fetal deaths and 31 (27.6%) neonatal deaths. There were no differences in maternal age, parity, or gestational age of delivery between male and female pregnancies.
  
  
  CONCLUSIONS
  Although the female preponderance did not reach statistical significance, the female tendency might still exist after a larger series analysis. The female tendency may be the result of the gender difference in monochorionic twins. The gender difference could provide research implications and a diagnostic warning for clinicians in monochorionic twin pregnancies before the presence of TTTS.
authors.affiliation: Department of Obstetrics and Gynecology, China Medical College Hospital, Taichung, Taiwan, R.O.C.
authors.forename: Y Y
authors.initials: YY
authors.lastname: Hsieh
authors.forename: F C
authors.initials: FC
authors.lastname: Chang
authors.forename: H D
authors.initials: HD
authors.lastname: Tsai
authors.forename: T Y
authors.initials: TY
authors.lastname: Hsu
authors.forename: T C
authors.initials: TC
authors.lastname: Yang
authors.forename: L S
authors.initials: LS
authors.lastname: Yeh
authors.forename: W C
authors.initials: WC
authors.lastname: Chang
mesh_terms: D005260:Female; D005330:Fetofetal Transfusion / Q000453:epidemiology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D015995:Prevalence; D012737:Sex Factors; D013624:Taiwan / Q000453:epidemiology