I have asked my bb doctor and she said we should not give 奶咀 especially after 2-3mths. She said because bb will concentrate on sucking 奶咀 and will delay his focus on learning other stuff. But I guess you all understand sometimes it's so hard not to give 奶咀 when he's crying for no reason. I try not to give to many times but I still need to give him 奶咀 if he cries at night...