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Risk factors for neonatal organ damage among newborns at gestational age > 34 weeks and umbilical arterial ph<7.00

      Objective

      Among newborns at 34 weeks or more with umbilical arterial (UA) pH<7.00, determine the risk factors for neonatal organ injury, as defined by Hankins et al (Obstet Gynecol 2002), within 72 hours of birth.

      Study design

      Retrospectively, all non-anomalous newborns delivered over 6 years (1997-2002) with gestational age (GA) >34 weeks and with UA pH<7.00 were identified. Each case of a newborn with end-organ damage within 72 hours of delivery was compared with the next four neonates with a low pH and no evidence of injury. P<0.05 was considered significant.

      Results

      Of 17,042 deliveries during 6 years, 14,656 parturients were at least 34 weeks or more. Umbilical arterial pH was obtained for 13,190 newborns and the prevalence of low pH was 0.6% (87/13,190). Of the 87 newborns with pathologic acidosis, 16% (95% CI 9 to 25) had evidence of multi-organ system injury (some cases involved more than one system), with the most common involving central nervous system (n = 8), followed by hematologic (n = 4), and three cases each of renal or hepatic injuries. The perinatal mortality for these 87 neonates was 34/1000 deliveries. A comparison of those with (n = 14) versus those without (n = 56) end-organ damage indicated the following risk factors to be significantly different: (1) gestational age between 34 and 36 weeks (OR 4.62, 1.19, 17.79); (2) seizure disorder in the mother (OR 15.00; 1.42, 158.00); and (3) an intrapartum sentinel event (OR 4.63, 95% CI 1.16,18.46). Inspection of the receiver operating characteristic curve indicates that pH of 6.92 may be the threshold that identifies newborns that will have damage to organs (true-positive rate 0.71 and false-positive rate 0.25).

      Conclusion

      UA pH <6.92 may be the threshold that identifies neonates who will have organ system injuries within 72 hours of delivery.