I'm on it to..Round two of it. I'm thinking everything's going to be fine. They say benadryl might (might) cause it also which is safe during pregnancy and I've also taken that. But it could also happen for no reason at all. So I try not to worry. You have to eat. Believe me I take it and even then I still get sick but it's better then not taking it at all.
I am on Zofran for HG and have been since 8 weeks (now 17). I looked up lots of info regarding safe use and the large majority of women had healthy babies. Cleft palates are also formed in first 10 weeks and can be due to diet so many doctors consider it could largely be down to HG (poor diet because of constant vomiting/nausea) rather than zofran itself. At the end of the day it's need first, I knew I wasn't getting the vitamins or water needed for the baby and after numerous hospitalisations I knew that zofran was my best hope of keeping the baby healthy and growing on target. By worrying about it you are showing you are a good mum.