Comparison of umbilical blood gas and acid-base status of small-for-date and normal Chinese newborns.

A prospective study of umbilical arterial blood gas in appropriate-for-gestational-age (AGA) and small-for-gestational-age (SGA) babies was performed at our hospital from August 1989 to July 1990. A total of of 512 cases were included, 432 cases in the AGA group and 80 cases in the SGA group, with gestational ages ranging from 26 to 42 weeks. Umbilical arterial blood was collected immediately after delivery of the newborns. Comparisons of maternal age, gestational age, birth body weight and body length of infants. Apgar scores at one minute and five minutes, cord arterial blood pH, pO2, pCO2, base excess, bicarbonate, total CO2, O2 saturation and O2 content between the AGA and SGA groups were taken into account. Our results demonstrated significant differences in birth body weight, birth body length, Apgar scores at one minute and five minutes and gestational age in the SGA group compared with those in the AGA group. The parameters of cord arterial blood gas were not correlated with gestational age in either group. The mean pH value in the AGA group (7.30 +/- 0.05) was higher than that in the SGA group (7.28 +/- 0.08). The same trend of difference was also noted between the AGA (7.30 +/- 0.04) and SGA (7.27 +/- 0.07) babies who were delivered by Cesarean section (p < 0.05). The latter results imply a more academic state in SGA babies which is independent of labor. Prepartum asphyxia plays an important role in determining the prognosis of SGA babies. We suggest routine umbilical cord blood gas and acid-base analysis at delivery to assess fetal asphyxia.