I was talking an anti malaria tablet which i found out is a folic acid antagonist before i knew i was pregnant can this harm my baby?

Yes, it's possible: Low Folic Acid levels in the first weeks after conception increases the risk of a baby having neural tube defects. I hope & pray your baby hasn't been adversely affected but there is increased risk, esp, if you were not taking Folic Acid or folate (folic acid) in early pregnancy. Blood tests & ultrasound can tell if your baby was harmed. Discuss with your doctor. See http://bit.Ly/19matnx.

Still taking it??: Some antimalaria tablets are not recommended in pregnancy at all, and some are safer (or at least have more data in pregnancy). Several drugs are Folic Acid antagonists. If you've stopped that drug and are now on prenatal folate, (folic acid) you may be okay. The first trimester is very important for organogenesis, though. Please discuss with your OB doctor.