parks textbook of preventive and social medicine 23rd edition * ninth revision of international classification of diseases (ICD) added that :(1) babies choosen for inclusion in perinatal statistics should be tjose above a minimum bih weight ie1000g at bih. (2)if bihweight is not available ,a gestational period of atleast 28weeks should be used if (1)&(2)is not available ,body length of atleast 35cm should be used .