The best fabric for infant clothing like onesies, bodysuits, rompers etc. would be any kind of knit organic cotton fabric. It could be jersey knit, rib knit or interlock knit. All these are very soothing, soft and comfortable but make sure that the GSM (grams per square meter) is somewhere between 120-200 GSM.
Jersey knit proves to be the best knit since its cost efficient and easily available as compared to others. In case you are buying/ making any accessories like hats, caps, socks etc then interlock and rib would be better.
Cotton is always the easiest and the best choice for newborn babies and infants below 24 months, because of its gentle and hypoallergenic nature, in few cases you can also choose fine wool as well. But given that wool is a little heavier, it might weigh the kid down in comparison to cotton. Its best to have atleast 95% cotton or more and the remaining 5% could be either jute, bamboo, linen, hemp etc. which are equally eco friendly and good for the skin.
Organic cotton a great choice since its very soft and supple, light in weight, smells nice because of its chemical free nature and non allergic even to sensitive skin.
Cotton spandex blend is a good choice for adult garments however not so much for infants since they don't really need that extra movement capability and the extra elasticity. Moreover, the above knits are somewhat elastic because of knit stitch.
Blankets and comforters
Talking about blankets and comforters, the best fabric again would be 100% cotton with pile cut weave, or simple pile fabric. Because blankets need to be highly water absorbent and easy care fabric and cotton is one of the most absorbent natural fibres.
Add some terry or pile on it and the fur like surface enhances the absorbent capacity and adds warmth and thermal insulation which is very important for kids .
Another great option is 100% organic cotton muslin fabric is also widely used for baby blankets and comforters and it is also cheaper than the pile cut cotton fabrics above. Organic cotton has proven to be hypoallergenic and best suited for sensitive skins.
GSM is also an important factor for blankets and comforters since these need to be thick. It's best to use muslin fabric of in range of 250- 400 gsm. However you also need to consider the fact that higher the gsm, more thick and heavy the fabric becomes, which reduces the breath ability of the fabric and makes it suitable for winter but not for summers.
Lighter gsm makes fabrics suitable for summer, but be very sure to use atleast 200 gsm otherwise it would be too light to use as a blanket.
Hope this helps you choose the best fabrics for your babies.
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