Analysis of risk factors for mother-to-infant transmission of HCV
In the present study, vaginal delivery itself did not increase the risk for transmission, compared with cesarean section. However, children who were delivered vaginally and whose mothers sustained a perineal or vaginal laceration had a 6-fold higher risk of becoming HCV-infected than did vaginally-delivered children whose mothers had no laceration. In contrast, no significantly increased risk was observed when an episiotomy was performed. The transmission rate of HCV did not differ between emergency and elective cesarean sections, although the number observed was small
In addition, every reduction in umbilical cord–blood pH by 0.1 increased the risk of mother-to-infant transmission of HCV by 4-fold (assuming a pH standard value of 7.27). An APGAR score of 9/10 at 1 and 5 min was noted for all these HCV-infected newborns
Birth weight of the newborn and gestational age did not increase the risk of mother-to-infant transmission, but we observed a trend for a higher birth weight of the child in women who sustained a perineal or vaginal laceration (mean weight, 2.93 vs. 3.18 kg; estimated relative risk [RR], 3.0; P=.082, logistic regression analysis). No increased risk of mother-to-infant transmission of HCV was observed in primipara or in mothers who experienced a premature rupture of membranes. Six (10%) of 58 mothers did breast-feed, but none of their children was HCV infected
Interactive effects of the risk factors investigated were subsequently evaluated by a multivariate analysis. Results of this analysis were similar to those obtained by univariate logistic regression, except for perineal or vaginal laceration (RR, 2.99; 95% confidence interval, 0.32–27.70) and umbilical cord–blood pH (RR, 5.0; 95% confidence interval, 1.06–23.80)
Follow-up investigation of childrenTo evaluate the course of the HCV infection in infected children and the clearance of maternal HCV antibodies in uninfected children, the 75 children were monitored for as long as possible. All 9 HCV-infected infants were singleton births and were surveyed for a minimum follow-up period of 11 week. The earliest time that 1 newborn was tested and HCV RNA could be detected was at the age of 9 days. Two other children were HCV RNA positive already at the age of 15 and 22 days, respectively. Eight of the 9 HCV-infected children had consistently positive RT-PCR results in the samples collected after the age of 1 month (in 2 children, HCV RNA could be still detected at the age of 5 years). One infected child with detectable HCV RNA became HCV RNA negative at the age of 15 months and remained negative thereafter
All 66 HCV-uninfected children were at least 5 weeks old when last tested for HCV viremia by PCR (median age, 28 weeks; interquartile range, 10–35 weeks). Altogether, 114 samples were collected from these HCV-uninfected children and tested for HCV-specific antibodies by ELISA. When ELISA results were analyzed in relation to the age of the children, a 50% probability of an HCV antibody–negative result was attained at the age of 9.6 months