i find if they dont have feet in them 0000 will be fine. I have found with both my DD's the all in one grows never have long enough legs if the feet are attached iykwim. My dd2 i about 3.5kg now and is 4 weeks old and in all 0000 cept the all in ones, with them i need 000. I would go for more 000's to be sure they fit.