title: Maternal immunoglobulin G avidity as a diagnostic tool to identify pregnant women at risk of congenital cytomegalovirus infection.
abstract: BACKGROUND
  The immunoglobulin (Ig) G avidity index (AI) is useful to detect primary cytomegalovirus (CMV) infection. However, because IgG matures with time, this index is not useful to detect a primary infection, unless measured at an appropriate time.
  
  
  OBJECTIVE
  We aimed to clarify the difference between using IgG AI and IgM positivity according to the stage of pregnancy to identify congenital CMV infection risk.
  
  
  METHODS
  We collected the serum samples from 1115 pregnant women who underwent maternal screening for primary infection (n = 956) and were referred to our hospital because of CMV IgM positivity (n = 155) or had abnormal fetal ultrasonography findings (n = 4). The same sera samples were used to measure CMV IgM, IgG, and IgG AI. An IgG AI of <35% was defined as low. Neonatal urine collected within 5 days after birth was examined by polymerase chain reaction to confirm congenital infection.
  
  
  RESULTS
  Fourteen mothers gave birth to infected neonates. The sensitivity, specificity, and negative predictive values of the low IgG AI group with IgM-positive samples to discriminate between women with congenital infection at ≤14 weeks of gestation were 83.3, 83.8, and 99.1, respectively, which were higher than those of other subjects. Uni- and multivariate analyses revealed that IgM positivity and low IgG AI were independent variables associated with congenital infection at any stage of pregnancy, except low IgG AI at ≥15 weeks of gestation.
  
  
  CONCLUSIONS
  Low IgG AI with IgM positivity at ≤14 weeks of gestation was a good indicator of congenital infection, which should prove useful in obstetric practice.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, University of Miyazaki, Japan; Graduate School of Nursing Science, Faculty of Medicine, University of Miyazaki, Japan. Electronic address: mkaneko@med.miyazaki-u.ac.jp.
authors.forename: Masatoki
authors.initials: M
authors.lastname: Kaneko
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, University of Miyazaki, Japan.
authors.forename: Masanao
authors.initials: M
authors.lastname: Ohhashi
authors.affiliation: Aisenkai Nichinan Hospital, Miyazaki, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Minematsu
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, University of Miyazaki, Japan.
authors.forename: Junsuke
authors.initials: J
authors.lastname: Muraoka
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, University of Miyazaki, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Kusumoto
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, University of Miyazaki, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sameshima
mesh_terms: D000914:Antibodies, Viral / Q000276:immunology; D000915:Antibody Affinity / Q000276:immunology; D003587:Cytomegalovirus / Q000276:immunology*; D003586:Cytomegalovirus Infections / Q000097:blood* / Q000175:diagnosis* / Q000276:immunology / Q000821:virology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology*; D007075:Immunoglobulin M / Q000097:blood; D007231:Infant, Newborn; D008297:Male; D009035:Mothers; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000097:blood / Q000000981:diagnostic imaging* / Q000276:immunology / Q000821:virology; D012306:Risk; D012680:Sensitivity and Specificity
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M
keywords: Congenital cytomegalovirus infection; IgG avidity; Immunoglobulin M; Screening; Serological