The Medela calma bottles are designed for breast fed babies. The nipple is different and has a mechanism inside that works so that baby has to work for every drop of milk, much like the breast. It doesn't leak or drip milk into baby's mouth and baby has 100% control over flow. I love it and am using it with my 6 week old until her mouth sores heal and she latches again. They are pricy but easy to clean so I'd just get one or two and wash between feeds and send the pumped milk in cheap storage jars. I also have some Avent bottles which are nice and wide neck with newborn nipples. They are ok but definitely drip/leak milk into baby's mouth.