High Maternal HBV Viral Load, but Not HBeAg Status, Predicts Mother-to-child Hepatitis B Transmission

By Liz Highleyman

Hepatitis B virus (HBV) infection is endemic in much of the world, and in these areas is it commonly spread through mother-to-child (vertical) transmission during pregnancy or delivery. While most people infected as adults will spontaneously clear the virus, some 90% of those infected as infants develop chronic infection.

As reported at the recent Digestive Disease Week 2008 conference in San Diego, Chandana Pande and colleagues from India conducted a study to identify potential risk factors for HBV transmission in utero.

As background, the investigators noted that maternal hepatitis B "e" antigen (HBeAg) positivity is associated with vertical HBV transmission, but as many as 90% of chronic HBV-infected patients are HBeAg negative despite being HBV DNA positive.

In the present study, pregnant women presenting for care were screened for hepatitis B surface antigen (HBsAg). If positive, their babies at birth were tested for HBsAg, HBeAg, and HBV DNA. Testing positive for any of these markers was considered as transmission of HBV to the newborn.

Results

• Of 11,524 pregnant women screened, 133 (1.2%) were found to be positive for HBsAg

• 23% were HBeAg positive and 64% had quantifiable serum HBV DNA.

• 127 women delivered babies, including 84 with live births at the researchers' hospital.

• Overall, 66% of infants were found to be infected with HBV based on umbilical cord blood samples.

• In 41% of infants, peripheral blood was also positive for HBV markers, indicating intrauterine (during gestation) rather than perinatal (during delivery) transmission.

• By HBeAg and HBV DNA status, transmission rates were as follows:

• HBeAg positive and HBV DNA positive: 79%;
• HBeAg negative and HBV DNA positive: 75%;
• HBeAg positive and HBV DNA negative: 66%;
• HBeAg negative and HBV DNA negative: 46%.

• Looking at maternal HBeAg and anti-HBe antibody status, HBV DNA level, mode of delivery (vaginal or Cesarean), and gestation period, only detectable maternal HBV DNA was significantly associated with increased vertical HBV transmission rate (P=0.025).

• A maternal HBV DNA cut-off of 1.5 x 105 copies/mL or greater had a high predictive value for maternal-fetal HBV transmission (area under the curve 0.63).

Conclusions

Based on these findings, the investigators concluded that, "Up to two-thirds of babies get exposed to the HBV infection from an infected mother," 41% by intrauterine transmission and the rest via the perinatal route.

They added that, "Maternal HBV DNA and not HBeAg positivity is associated with high transmission rate."

5/30/08

Reference
C Pande, A Kumar, S Patra, and others. High maternal hepatitis B virus DNA levels but not HBeAG positivity predicts perinatal transmission of hepatitis B to the newborn. Digestive Disease Week (DDW) 2008. San Diego, CA. May 17-22, 2008. Abstract 252.