Fluoride during pregnancy

Hi, I just found out not long time ago that I am pregnant (aprox 7 weeks). I had a dentist examination today and they said that I have some small decay in forming and they want to apply a very small amount of fluoride on it (2 teeth) to protect the teeth. I asked them if thats safe during pregnancy and they said that they put very small amount and it is safe. I googled it afterwards and I read that fluoride treatments can harm the baby… but it is still wasn’t a big amount but I am still very concerned 😟 Could this harm the baby? Many thanks in advance