Figure 2.

Changes in mortality over 24 hours according to time of birth by one or two hour intervals for spontaneous live births of infants without congenital malformation, Sweden 1973-95. Dashed lines represent reference mean values over 24 hours (χ² test for difference over 24 hours, P<0.0001 for infant mortality and early neonatal mortality by both one and two hour intervals; P=0.005 and 0.007 for early neonatal mortality related to asphyxia by one and two hour intervals, respectively)