It’s perfectly normal for your breasts to leak while you are breastfeeding, especially in the early days.
It happens when your breasts are particularly full of milk or when something makes your body think that breastfeeding has happened, activating your “letdown reflex”. It can also be an emotional response – some women report their breasts leaking when they hear their baby crying.
There’s no way of stopping your breasts from leaking. If you are practicing responsive feeding then this will help your body adjust so it is making enough milk to feed your baby – working on a “supply and demand” basis. Using breast pads will help stop milk leaking onto clothing. For most mothers the leaking reduces or stops as breastfeeding becomes more established.