Antiviral Drug Before Birth Reduces C-Section Rate for HSV

DALLAS, July 11 -- Treatment with one month of an antiviral drug before birth significantly reduces the need for a Cesarean among women with chronic genital herpes, found investigators here.

•Explain to interested patients that active genital herpes lesions or prodromal symptoms at delivery are regarded as indications for a Cesarean section to avoid transmission of the virus to the infant.

•Note that this study shows that antiviral medication during the last weeks of pregnancy reduces the risk of herpes outbreaks, as well as the need for a Cesarean.

•Explain, however, that a large proportion of HSV neonatal cases occur in infants whose mothers were asymptomatic at the time of delivery.

In a randomized, placebo-controlled trial, the antiviral Valtrex (valacyclovir) reduced the rate of clinical herpes simplex virus (HSV) at delivery by 70%, according to Jeanne Sheffield, M.D., of the University of Texas Southwestern Medical Center.

As a result, the use of Valtrex reduced the number of Cesarean sections performed to avoid HSV transmission to infants by the same proportion, Dr. Sheffield and colleagues reported in the July issue of Obstetrics & Gynecology.

The finding "will help immensely in giving doctors stronger evidence in using this treatment," Dr. Sheffield said.

Current practice is to offer a Cesarean to any women with an active herpes lesion or prodromal symptoms at the time of labor, but as many as 70% of neonatal infections occur in babies of women who were asymptomatic going into labor, Dr. Sheffield and colleagues said.

An earlier meta-analysis had suggested that antiviral therapy in the last week of pregnancy might reduce the risks of transmission, so Dr. Sheffield and colleagues randomized 350 pregnant women with a history of genital herpes to get placebo or Valtrex at 500 mg twice a day starting at week 36 of the pregnancy.

The study cohort consisted of 170 women in the Valtrex group and 168 in the placebo group; 12 women were lost to follow-up. The researchers found:

• The proportion of women with clinical genital HSV at delivery was 13% in the placebo group and 4% in the Valtrex group. The odds ratio was 0.30, with a 95% confidence interval from 0.12 to 0.73, which was statistically significant at P=0.009.

• Valtrex significantly decreased the likelihood of a positive herpes culture. The odds ratio was 0.18, with a 95% confidence interval from 0.04 to 0.82; P=0.02.

• Similarly, the medication reduced the likelihood of a positive herpes finding on polymerase chain reaction testing. The odds ratio was 0.28, with a 95% confidence interval from 0.11 to 0.72; P=0.01.

• Finally, the proportion of C-sections for HSV was 4% in the Valtrex group compared to 13% in the placebo group. The odds ratio was 0.30, with a 95% confidence interval from 0.12 to 0.73, which was statistically significant at P=0.009.

"Besides reducing the number of herpes outbreaks at birth, we also dropped the numbers of women without symptoms who were shedding the virus into the birth canal," Dr. Sheffield said.

The researchers also evaluated the safety of the approach: Among the mothers, there was no serious morbidity, with mild nausea and vomiting, headache, and dizziness being the most common adverse effects. No adverse events were seen in the infants, although one child in the placebo group died without explanation at term.

None of the infants was diagnosed with HSV in the first month after birth.

The study was partly supported by GlaxoSmithKline, which makes Valtrex.