My OB just said "a medium-large baby" (8lb4oz). I had some 0000's and 000's that I took to hossy - the 0000's fit him for about 2 months, and we're just moving out of 000's in myer brand and in between 00's and 0's now in bonds, but still wearing 0000 singlets. Singlets last for ages in the smaller sizes, it's the feet that muck up sizes in wondersuits. Beanies too are strange sizings, better to have small not xs maybe, but with a tie to size them.

Good luck!