Don't buy newborn clothes until they are born!! Or at least don't remove the tags.

My twin sisters (12 months old), were born at 33 weeks gestation (1600g & 1670g) and were in 000000 when they came home from hospital at 5 weeks old. If it eren't for their length they would barely be in 00's now at 12 months. They weigh less than 8 kilos.