title: Risk factors for mother-to-child transmission of hepatitis C virus: Maternal high viral load and fetal exposure in the birth canal.
abstract: OBJECTIVE
  Mother-to-child transmission (MTCT) is the major transmission pathway of hepatitis C virus (HCV) in children. However, its risk factors remain unsettled for introduction of putative intervention.
  
  
  METHODS
  Pregnant women screened for HCV and MTCT in children born to antibody-positive mothers were prospectively studied in Tottori, Japan.
  
  
  RESULTS
  Among 41 856 screened women, 188 (0.45%) were HCV antibody-positive, of whom 61% had detectable HCV RNA. While 10 of the 34 children (29%) born to high viral load (HVL: ≥6.0 × 10(5)  IU/mL) mothers were infected, none born to RNA-detectable but non-HVL mothers were infected (P < 0.001). MTCT among vaginally delivered children born to HVL mothers was analyzed. Children delivered after 4 h or more of labor were more frequently infected than were those born within 4 h of labor (P = 0.019). Premature rupture of fetal membranes was significantly more common in infected children than in uninfected children (P < 0.001). Durations of membrane rupture and labor were longer in infected children than in uninfected children (P = 0.008 and P = 0.040, respectively). Elective cesarean section that eliminates these risk factors, other than HVL, significantly reduced MTCT from nine of 22 (41%) to none of nine children (0%) (P = 0.032).
  
  
  CONCLUSIONS
  Our data suggest that contamination of the fetus in the birth canal with infected maternal blood is a major risk factor for HCV MTCT, in addition to maternal HVL. To rationalize intervention by elective cesarean section, the natural history of infected children should be carefully evaluated.
authors.affiliation: Division of Pediatrics and Perinatology             Department of Virology, Faculty of Medicine, Tottori University, Yonago             Tsuyama Central Hospital, Tsuyama             Tottori Prefectural Central Hospital, Tottori             Matsuda Pediatric Clinic, Kurayoshi             St. Luke's College of Nursing, Tokyo             Radiation Effects Research Foundation, Nagasaki, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Murakami
authors.forename: Ikuo
authors.initials: I
authors.lastname: Nagata
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Iitsuka
authors.forename: Manabu
authors.initials: M
authors.lastname: Okamoto
authors.forename: Shunsaku
authors.initials: S
authors.lastname: Kaji
authors.forename: Tadataka
authors.initials: T
authors.lastname: Hoshika
authors.forename: Ryu
authors.initials: R
authors.lastname: Matsuda
authors.forename: Susumu
authors.initials: S
authors.lastname: Kanzaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shiraki
authors.forename: Akihiko
authors.initials: A
authors.lastname: Suyama
authors.forename: Shigeo
authors.initials: S
authors.lastname: Hino