title: Transplacental total IgG transfer in twin pregnancies.
abstract: OBJECTIVE
  In twin pregnancies, factors that influence total umbilical cord IgG concentration and IgG transfer ratio are not well known.
  
  
  METHODS
  Blood samples were prospectively collected from 57 twin pregnancies. Stepwise multivariate regression analysis was used to evaluate the association between total IgG levels in the umbilical cord blood and IgG transfer ratio according to serum IgG concentration, pregnancy chorionicity, the presence of abnormal umbilical artery pulsatility index, intrauterine growth restriction, gestational age at delivery (GAD), birthweight, and placental weight.
  
  
  RESULTS
  Umbilical cord IgG concentration showed a positive correlation with serum IgG concentration and GAD; levels were significantly lower in monochorionic compared with dichorionic pregnancies. IgG transfer ratio also increased with GAD but was inversely correlated with serum IgG concentration levels.
  
  
  CONCLUSIONS
  In twin pregnancies, besides serum IgG concentration and GAD, chorionicity also influences umbilical cord IgG concentration. Monochorionic twins have lower IgG cord concentration than dichorionic twins.
authors.affiliation: Department of Obstetrics and Gynecology, São Paulo University Medical School, Sao Paulo, Brazil.
authors.forename: Sonia C L
authors.initials: SC
authors.lastname: Stach
authors.forename: Maria de L
authors.initials: Mde L
authors.lastname: Brizot
authors.forename: Adolfo W
authors.initials: AW
authors.lastname: Liao
authors.forename: Rossana P V
authors.initials: RP
authors.lastname: Francisco
authors.forename: Patricia
authors.initials: P
authors.lastname: Palmeira
authors.forename: Magda
authors.initials: M
authors.lastname: Carneiro-Sampaio
authors.forename: Marcelo
authors.initials: M
authors.lastname: Zugaib
mesh_terms: D001724:Birth Weight; D002823:Chorion / Q000276:immunology; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D005865:Gestational Age; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007231:Infant, Newborn; D008297:Male; D010920:Placenta / Q000276:immunology*; D011247:Pregnancy; D059285:Pregnancy, Twin / Q000276:immunology*; D011446:Prospective Studies; D014430:Twins, Monozygotic
chemical_list: D007074:Immunoglobulin G
keywords: IgG concentration; immunoglobulins; maternal transfer; multiple pregnancy