These tights fit great. my daughter is 8 months old and very tall for her age. I ordered the 12-24 mo size and they are a little long but fit great around the middle (She is also very narrow waisted, so if you have a somewhat chunky baby, the fit may not be as great/comfortable)
Organic vs non organic was not a concern of mine when I purchased these, I was only looking for solid black cotton tights that tapered at the ankle. The cotton is very luxurious and for around $10, I'd buy these in other colors. Very warm and high quality tights.