It will not affect the baby at all. And if you think it through, you will realize it cannot possibly make a difference. Your baby will be exposed the the drug the whole time you're taking it, before delivery; then you'll stop taking the drug -- so the baby will no longer be exposed to the through your breast milk. And even if she were, it would do no harm. This type of drug is used all the time in newborns; side effects almost never happen.
Really, you need to stop worrying about this. Follow your doctor's advice; s/he knows what is best for both the babys health and yours.
Thank you Dr. Hansfield for your reply. I am also concerned about breastfeeding and taking the Valtrex. How would it affect the baby?
Thank you again.
One additional clarification: All of the data on preventing herpes-driven cesarean section are in women with genital HSV-2, not HSV-1. I'm not certain whether the ACOG and CDC recommendations about acyclovir (or valacyclovir) late in pregnancy are intended for moms with histories of genital HSV-1. My judgment is that treatment is still a good idea, and I certainly would want it to be done if my daugher, wife, or other person close to me were in your situation. But you could discuss this aspect with your obstetrician. Consider printing out this entire thread as a starting point for discussion at your next prenatal visit.
Welcome to the forum. I'll try to help.
There are two reasons for anti-herpes therapy the last 3-4 weeks of pregnancy in women with histories of genital herpes. First is to prevent a recurrent outbreak that would increase the chance of HSV transmission to the baby and would force an otherwise unnecessary cesarean section. The second is to lower the chance of transmission of HSV to the baby. This has not actually been studied, but it's a reasonable assumption that it does further reduce the very low risk of such transmission.
The anti-herpes drugs are totally safe late in pregnancy, for both baby and mom. It's good to be conservative about drug treatment early in pregnancy, but in the second half of pregnancy it's rarely a problem with any drug and certainly not with acyclovir or valacyclovir. Your Ob knows this and would not have prescribed it unless s/he made the judgment that the benefits outweighed the risks.
Bottom line: Neonatal herpes is rare, but if it happens, it is extremely serious, often fatal and with bad developmental problems in some surviving kids. Your Ob is following standard the recommendations of CDC, the Amercan College of Obsetricians and Gynecologists, and all STD/herpes experts. You should follow the advice. Or at least discuss it with him or her before deciding on your own not to take the drug.
Best wishes for successful completion of your pregnancy and for your growig family--
HHH, MD