I've been in a generic form for all 5 of my pregnancies called valicyclover. They've put me in it every time in the third trimester.
Ok cause I was given valtrex for cold sores, but it's like 8 pills to take in two days, not an every day occurrence, plus I have a prescription ointment for the cold sores. Luckily I never had an outbreak while pregnant cause my lips will fill up with cold sores to either down my chin or up my nose, that's annoying enough so I can only imagine genital, I was given hydrocodone recently at 20 weeks for a kidney stone I took one to help pass the stone, if that's trusted enough I think you will be ok, I know it's hard not to worry, I was in a bad car accident with my last at 35 weeks and was terrified of taking any kind of medicine.
Is this for genital herpes or herpes simplex like cold sores?
To the best of my knowledge you can take that kind of medication as often as needed. It will never be the cure but it will help your outbreaks to dry up as much as possible and should start providing you some relief within a few days of using it. Chances are that if you are having reoccurring outbreaks then you may need to initially take a stronger dose to prevent the outbreak getting worse; then once that has healed you can ask to be put on the supressive dose which aims to prevent you from getting another outbreak.