Is the determination of umbilical cord arterial blood gases necessary in all deliveries? Analysis in a high-risk population.

Umbilical cord arterial blood gas (UCABG) analysis is recommended in addition to Apgar scoring for assessing newborns. A prospective study was performed to determine whether UCABG values should be obtained in all deliveries, or only in selected deliveries in which the UCABG values are likely to be informative. During a predefined study period, maternal and neonatal data were collected for all live births (n = 604). UCABG test results were available for 505 births. Of these, 98 (19.4%) had UCABG pH < 7.2 (acidotic group), and they were compared with the other 407 live births (nonacidotic group). There were significantly more primiparous women in the acidotic group, whereas grandmultiparity (parity > 7) was significantly lower. The first and second stages of labor were significantly prolonged and there were more assisted births in the acidotic group. Fetal distress and the incidence of Apgar scores < 3 were significantly higher in the acidotic group. The selective determination of UCABG values in primiparous pregnancies, prolonged labors, assisted deliveries. or in the presence of fetal distress may be more informative than universal UCABG determination. Although these factors were highly sensitive, their specificity was poor; thus we cannot recommend criteria for the selective determination of UCABG values.