In the case of the nipple hole being round, milk may gush out when you turn the bottle upside down after making the formula in the bottle.

This phenomenon is caused by the air in the bottle expanding due to the warm temperature of the milk, and the milk is then pushed out.

After a while, it will settle down, and the milk will start dripping instead – this is the time to bottle feed your baby.

You may also remove the screw cap once after making the formula in the bottle, then screw the screw cap on again so that the air pressure in the bottle is reduced and the milk does not gush out easily.