My baby is almost 6 months old. I breastfed for the first month and a half. She was not gaining weight but loosing it and I felt really bad at not even a month old i was having to feed her like 6 oz every hour and she still screamed because she was hungry. So I gave her Enfamil with iron. BAD IDEA, she was so gassy and could not poop. So I switched her to Enfamil for babies with fussiness. I had her on it for about 3 months. still not happy she was spitting up so much and pooping was still hard, So I put her on Similac Organic, She is doing fantastic, less spit up she is pooping right, and no gas, SIMILAC ORGANIC IS GREAT!! a little expensive but worth it.