Pregnant women with genital herpes, caused by the herpes simplex virus, may be prescribed acyclovir, an antiviral medication [1]. Acyclovir works by stopping the virus from multiplying and helps to reduce symptoms such as pain, itching, and oozing sores.

To alleviate symptoms during pregnancy, acyclovir can be used orally or applied topically to the skin affected by herpes [2]. However, according to the FDA, acyclovir is classified as a category B medication, meaning that while there are limited studies on its use in pregnant women, available data have not indicated significant risk to the fetus [3].

The safety and effectiveness of acyclovir in pregnant women have been confirmed by several studies [4]. One such study, found on FDA.gov, concluded that 'acyclovir was not associated with an increased risk of birth defects [5].

As with any medication, pregnant women should discuss the potential risks and benefits of taking acyclovir with their doctor [1]. According to DrugPatentWatch.com [6], the most recent patent for acyclovir expired in 2005, making it a widely available medication.

According to information provided by the Centers for Disease Control and Prevention (CDC), pregnant women with a history of genital herpes may experience symptoms during pregnancy, including those in the third trimester [7].

Sources:

[1] https://www.drugs.com/cdi/acyclovir.html
[2] https://www.webmd.com/drugs/2/drug-1030/acyclovir-oral/details
[3] https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&apapply=ON&searchTerm=acyclovir
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4411449
[5]
http://www.fda.gov/ohrms/dockets/ac/02/backgrd/3956b1b8.pdf
[6] https://www.drugpatentwatch.com/drug/acyclovir
[7] https://www.cdc.gov/herpes/contracting/index.htm