Yes it’s safe. Usually the gynaes at KKH would prescribed 5mg folic acid. These are generic folic acid and not the “branded” ones. Most off the counter folic are in mcg which is a lot lesser. My gynae shared with me to either buy from kkh pharmacy or get the guardian one that is usually packaged like normal meds because the so called max of 1000mcg (1mg) is a generic rule for safety. However, once you’re pregnant, in the whole of first trim, you should take 5mg. Thereafter, in second trim, not necessary because multi vits for pregnancy is more impt than the high dose of folic. Your baby does not need that much folic anymore because it’s structure would have already been formed. It needs other vitamins and nutrients from second trim onwards to have a balance of different vitamins for overall development.
best to seek your gynae's advice.