The aim of this study was to assess prospectively acid-base changes af
ter severe birth acidaemia. Fourty-five term babies with severe acidae
mia (median umbilical artery pH 6.99 [Range 6.74-7.05], mean base defi
cit 16.3 [SD 3.7] mmol/l) were prospectively identified. Pathological
cardiotocographs were present in 32 (71%) prior to delivery and 39 (87
%) were delivered operatively; 27 for fetal distress. Sixteen required
intubation. At one hour of age, median pH was 7.29 [Range 7.04-7.45]
and the change in pH correlated with one hour pCO(2) (r = 0.62 p < 0.0
01). pH measurements were obtained in 11 of the 16 babies with a 1 hou
r pH less than or equal to 7.25 and all values had recovered by this t
ime. Five of this group were receiving oxygen. Of the 11 babies admitt
ed to NICU, 1 died and 3 had evidence of encephalopathy, all of which
were normal at follow-up [2-12 months]. Recovery of pH after severe bi
rth acidaemia was evident at 1 hour of age and would appear to be comp
lete by 4 hours.