Speaking of the bibs on the site, I could see a modern re-interpretation of some of the ideas. The exception might be the bibs with straps or drawstrings as those may have safety issues. Bibs were knitted, crocheted, or sewn - simple, delicate, or fancy. Surely, new mothers of the day did pay attention to necessary, utilitarian clothing items.
I took 3 history of costume classes in college and none of them really talked about children's clothing. I did a quick browse at Amazon and found three books I wish I could look at more closely. Most books on the subject start in the Victorian age. There seems to be more information available for that time period and forward.