Twin study: Relationship between birth weight, zygosity, placentation, and pathologic placental changes

M. A. Ramos-Arroyo, T. M. Ulbright, P. L. Yu, J. C. Christian

Research output: Contribution to journalArticle

57 Scopus citations

Abstract

We examined the placentas of 182 like-sexed live-born twins: 73 placentas (40.1%) were monochorionic and 109 (59.9%) were dichorionic. All twin pairs with monochorionic placentas were monozygotic (MZ), but 28.9% of pairs with dichorionic placentas were MZ. Analysis of birth weights demonstrated that dichorionic and dizygotic (DZ) twins were heaviest, and suggested that the chorion status is a more important determinant of birth weight than zygosity. Vascular anastomoses were identified only in monochorionic placentas and occurred in 79.5% of cases. All placentas with deep anastomoses had superficial anastomoses. A higher proportion of velamentous and marginal insertions of the umbilical cord in monochorionic placentas (27.4%) compared to dichorionic placentas (13.8%) supports the belief that lateral placental growth is greatest in twin gestations in which the embryos are initially most closely apposed - The theory of trophotropism.

Original languageEnglish (US)
Pages (from-to)229-238
Number of pages10
JournalActa geneticae medicae et gemellologiae
Volume37
Issue number3-4
DOIs
StatePublished - 1988

ASJC Scopus subject areas

  • Genetics(clinical)

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