Abstract: Objective  To investigate the value of ultrasound measurement of umbilical artery PI, RI, S/D combined with serum hypoxia inducible factor 1α(HIF-1α), free estriol(FE3) in the diagnosis of fetal distress(FD) and its correlation with the severity of the disease in children. 
Methods  A total of 100 pregnant women with FD in our hospital were selected as the observation group, and 30 healthy pregnant women without FD were selected as the control group. All patients underwent ultrasound examination and serum HIF-1α and FE3 determinations. The levels of PI, RI, S/D, HIF-1α, and FE3 were compared between two groups. Receiver operating characteristic curve(ROC) and area under ROC(AUC) were used to analyze the diagnostic value of PI, RI, S/D, HIF-1α, and FE3 for FD. Pearson correlation analysis was performed to analyze the correlation of PI, RI and S/D with HIF-1α and FE3. Logistic regression equation was used to analyze the influencing factors of FD children′s condition. 
Results  PI and FE3 in the observation group were lower than those in the control group, and RI, S/D and HIF-1α were higher than those in the control group(P＜0.05). In pregnant women with FD, umbilical artery PI measured by ultrasound was positively correlated with FE3, and negatively correlated with HIF-1α. RI and S/D were negatively correlated with FE3 and positively correlated with HIF-1α(P＜0.05). ROC curve showed that the AUC of combined detection of all indicators was the largest, and the optimal sensitivity and specificity were 91.00% and 83.33% respectively. Logistic regression analysis showed that pregnancy-induced hypertension, gestational diabetes mellitus, umbilical artery PI, RI, S/D and serum HIF-1α and FE3 levels were all factors influencing the severity of FD(P＜0.05). 
Conclusion  The ultrasound measurement of umbilical artery PI, RI, S/D in pregnant women with FD is related to the expression of serum HIF-1α and FE3. The combination detection of these indicators can improve the diagnostic efficiency of FD, and guide clinical treatment and prognosis evaluation.

Key words: fetal distress, umbilical artery, pulsation index, resistance index