Prenatal risk factors for neonatal asphyxia: how risk for each? / 中国当代儿科杂志

<p><b>OBJECTIVE</b>Neonatal asphyxia is the third leading cause of neonatal death and main cause of long-term neurodevelopmental handicap throughout the world. Prevention is more important than treatment. Most previous reports are limited to retrospective investigations of the relationships between some prenatal risk factors and low Apgar scores. This study was designed to prospectively investigate the relationship between prenatal risk factors and neonatal asphyxia and the influence of single or multiple risk factors on the incidence of neonatal asphyxia, and examine significant risk factors for neonatal asphyxia.</p><p><b>METHODS</b>From April 2002 through October 2004, a total of 10 376 live-born newborns were enrolled. Forty-six prenatal risk factors were investigated. Neonatal asphyxia was diagnosed based on the following four items: 1. 1-min Apgar score <or=7; 2. Umbilical artery blood pH<7.20; 3. At least one organ had evidence of asphyxial injury; 4. Other causes of low Apgar score were excluded. The number, the constituent ratio and the exposure frequency of newborns with single or multiple risk factors were counted. The influence of risk factors on the incidence of asphyxia was analyzed. The significant risk factors were screened by single logistic regression analysis and forward stepwise conditional multiple logistic regression analysis, with enrolled threshold alpha<or=0.05, excluded threshold alpha>or=0.10 and p<0.05 as significant. The OR and 95%CI were calculated for each significant risk factor.</p><p><b>RESULTS</b>Of the 10 376 newborns, 8 530 cases (82.21%) had 1-9 risk factors, and asphyxia occurred in 117 cases (1.13%) out of the 8 530 cases. In the 1 846 cases without risk factors, none had asphyxia (x2=25.6, p<0.01). The incidence of asphyxia increased with increasing numbers of risk factors, from 0.23% in newborns with one risk factor to 14.29% in newborns who had nine risk factors (r=0.96, p<0.01). Twelve significant risk factors identified were as follows: ominous fetal heart rate patterns (OR=17.1,95%CI:11.2-25.9), placenta abruption (OR=15.2, 95% CI: 4.5-51.8), maternal lung diseases (OR=11.5, 95% CI:1.4-91.3), fetal acidosis (OR=6.1, 95% CI:1.5-24.1), placenta previa (OR=5.0,95% CI:1.5-16.9), breech delivery (OR=4.5, 95% CI: 2.1-9.9), meconium stained amniotic fluid (OR=3.2, 95% CI:2.2-4.8), forcepsjassisted delivery (OR=3.2, 95%CI: 1.1-9.9), prolonged labor (OR=2.94, 95%CI:1.5-5.8), abnormal utero contraction (OR=2.8, 95% CI:1.7-4.6), and premature delivery (OR=2.5,95%CI:1.4-4.8). Cesarean section had a protective effect (OR=0.6, 95% CI:0.4-0.9) (all p<0.05).</p><p><b>CONCLUSIONS</b>It is very important to prevent perinatal asphyxia by systematically examining prenatal risk factors and giving interventions for the newborns with risk factors, especially those with the above significant risk factors or with multiple risk factors. Proper cesareon section according to indications might be helpful to decrease the incidence of birth asphyxia.</p>

Clinical study on improving the diagnostic criteria for neonatal asphyxia / 中华儿科杂志

<p><b>OBJECTIVE</b>Diagnosing neonatal asphyxia solely according to Apgar score may lead to misdiagnosis. The aim of this study was to explore new and more accurate diagnostic criteria for neonatal asphyxia.</p><p><b>METHODS</b>Totally 10 376 live born neonates in our hospital were consecutively enrolled into the study. The following five items related to birth asphyxia, i.e., antepartum high-risk factors, Apgar scores, umbilical artery blood pH, organ injury, differential diagnosis on the causes of low Apgar score cases were examined and registered. The relationship among the first 4 items were analyzed. By differential diagnosis, the sensitivity and specificity of each index on diagnosing asphyxia and their complementary value on each other were investigated.</p><p><b>RESULTS</b>The items correlated well with each other (P < 0.01 or < 0.05) but were not entirely parallel and consistent; they could complement but could not substitute for each other. The sensitivity of antepartum high-risk factors, low Apgar scores, umbilical artery blood pH < 7.00 and organ injury was 100%, 100%, 44.44% and 100%, while the specificity was 17.99%, 98.90%, 96.05% and 96.62%, respectively. Of the 230 low Apgar score cases in this series only 50.9% coincided with asphyxia. For the 230 cases, when low Apgar score was combined with umbilical artery blood pH < 7.00, the sensitivity and specificity were 41% and 99.1% and when low Apgar score was combined with umbilical artery blood pH < 7.20, the sensitivity and specificity were 100% and 29.20%, respectively. After organ injury was added, the specificity was increased to 65.49%. When differential diagnosis was further added to exclude the other causes of low Apgar score cases, the misdiagnosis rate was minimized.</p><p><b>CONCLUSION</b>Up to now, no single accurate index for diagnosing neonatal asphyxia is available. In order to increase diagnostic bases and reduce misdiagnosis, the criteria of sole Apgar score should be replaced by multi-index diagnostic criteria. Based on the present study, a set of integrated diagnostic criteria for neonatal asphyxia is proposed: (1) prenatal high-risk factors, (2) low Apgar scores (respiratory depression must present), (3) umbilical artery blood pH < 7.00, if only pH < 7.20, the items (2) (4) (5) must be present, (4) hypoxic-ischemic organ injury (at least one organ dysfunction), (5) the other causes of low Apgar scores should be excluded. The last 4 indexes should all be met and the first one serves as reference. If multi-organ (three or more organs) dysfunction and (or) hypoxic-ischemic encephalopathy are present, severe asphyxia can be diagnosed.</p>