Importance of using standardized birth weight increments to report neonatal mortality data.

Neonatal mortality statistics are frequently reported in 100-g increments of birth weight. We tabulated our mortality statistics using two methods of incrementation: 500 to 599 g, 600 to 699 g, 700 to 799 g, etc. (method A) and 501 to 600 g, 601 to 700 g, 701 to 800 g, etc (method B). In each 100-g weight group, the mortality was less using method B. The average reduction in mortality using method B was 4.1%. Use of the two different methods creates difficulty in making meaningful comparisons of various published reports. We recommend that all future studies use method A, as that method is more consistent with previous recommendations of the World Health Organization.