Drinking whilst pregnant at any stage of your pregnancy can cause harm to your baby and the more you drink, the greater the risk. This is why it is recommended that the safest approach is to not drink alcohol at all during pregnancy.
If you are pregnant and drank a small amount of alcohol before you knew you were pregnant, and stopped when you found out, the risk of harm to your baby will be low. However, if you are worried you should talk to your doctor or midwife.
Drinkaware has more information and advice for mothers-to-be who have questions about alcohol during pregnancy.