my daughter is 6 weeks old i have been using the drop in since she was about a week old since breastfeeding wasn't working ever since then she was spitting up a lot and was put on reflux medicine while i had to wait for 4 days for the medicine to come in due to holiday weekends my ped suggested dr. brown bottles and she hardly spit up at all the couple times i used to bottles she spit up many times i wouldn't suggest these bottles to anyone! Plus you keep have to buy liners and 50 of them are about 5 dollars 5 dollars every week no thank you! Plus i would try taking these bottles out when we went...