Thats the problem with fawn calves though.  It seems nobody reports it. If you have one you might blame it on being premature.  I know my friends out at Rawlins Wyo. wouldnt know if they had one, They calve on a 30,000 acre pasture.  The first one I had I thought it was a premie.  Then the second I thought I messed up nutritionally somewhere, then other heifers bred differently calved and there were no problems,  then the third came, so I did some research and figured out what was going on.