• 1
    Van Jaarsveld CH, Johnson L, Llewellyn C, Wardle J. Gemini: a UK twin birth cohort with a focus on early childhood weight trajectories, appetite and the family environment. Twin Res Hum Genet 2010;13:728.
  • 2
    Price TS, Freeman B, Craig I, Petrill SA, Ebersole L, Plomin R. Infant zygosity can be assigned by parental report questionnaire data. Twin Res 2000;3:12933.
  • 3
    Benirschke K, Kaufmann P. Multiple pregnancy. In: Benirschke K, Kaufmann P, eds. Pathology of the Human Placenta. New York: Springer-Verlag, 1995. 4th edition. pp. 790904.
  • 4
    Hall JG. Twinning. Lancet 2003;362:73543.
  • 5
    Cleary-Goldman J, Morgan MA, Robinson JN, D’Alton ME, Schulkin J. Multiple pregnancy: knowledge and practice patterns of obstetricians and gynecologists. Obstet Gynecol 2004;104:2327.
  • 6
    Fisk NM, Bryan E. Routine prenatal determination of chorionicity in multiple gestation: a plea to the obstetrician. Br J Obstet Gynaecol 1993;100:9757.
  • 7
    Bessis R, Papiernik E, . Echographic imagery of amniotic membranes in twin pregnancies. In: Gedda L, Parisi P, editors. Twin Research 3: Twin Biology and Multiple Pregnancy. New York: Alan R Liss, 1981,1837.
  • 8
    Sepulveda W, Sebire NJ, Hughes K, Odibo A, Nicolaides KH. The lambda sign at 10–14 weeks of gestation as a predictor of chorionicity in twin pregnancies. Ultrasound Obstet Gynecol 1996;7:4213.