my osfms fit my daughter from 4 months to 16 months before some of them got too snug around the waist. strangely enough I have some cushie tushie coutures that fit and some that don't, go figure... we're still using babycheeks, cute tooshies and hautes though and these are osfm and they still fit her but I only started using these around 8 months so don't know if they fit a young baby well or not.