I don't know how much help this is, but I checked some sites I knew of that sell infant/childrens' patterns.
http://www.oldpatterns.com/ might be a good place to start, although they don't have much listed for sale right now. One item they have that might interest you is listed in the sewing book section, and it's a correspondence course in sewing that covers maternity/infant clothing. It's from the 20's, though, and I'm not 100% sure how much of a change there was in infant's fashion between the 20's and the 40's. Also, pastpatterns.com sells some vintage patterns that would be appropriate. Again not much listed in the way of infant's patterns, but worth a look.
So far i only came up with one picture of an infant, and it's in
Germany At War In Color by Lt. Col. George Forty. It looks like he's wearing a baby blue knit sweater. Not really clear what he's wearing underneath. If you can knit, knitting books from the period occasionaly come up on ebay.
One thing about infant's patterns from the period that I found on oldpatterns.com. It seems that they were most generally pre-cut with no instructions and little or no markings on the patterns peices.
Hope this helps.
