my baby is premature so she was 1st not able and then not allowed by her dr to suck for like 1 month .now that dr has permitted her she doesn't like it and also doesn't have that strong sucking power. I used to express milk for her but the flow has gradually reduced. I have read that the milk flow gradually reduce when you express it esp via using hand pump. I use AVENTs. My baby is 99% on formula milk now and she seems fine with that too.