Fetal pulse oximetry: relationship between oxygen saturation at second stage of labor and the umbilical artery pH at birth - Revista Brasileira de Ginecologia e Obstetrícia

Purpose: to study the correlation between fetal oxygen saturation measured by pulse oximetry during second stage of labor and umbilical artery pH at birth. Patients and Methods: fetal oxygen saturation (FSpO2) was monitored by pulse oximetry during the second stage of labor in 64 singleton pregnancies at term, with vertex presentation. Umbilical blood was sampled immediately after delivery for subsequent measurement of venous and arterial blood gases and pH. All fetuses maintained FSpO2 > or = 30% through the first stage of labor, until the start of second stage. Results: the mean FSpO2 at the second stage of labor correlated significantly with umbilical artery pH at birth (n = 64, r = 0.79, p <0.001). There was no significant corre-lation between FSpO2 at the second stage of labor and umbilical artery oxygen saturation at birth. Conclusion: fetal oxygen saturation measured by pulse oximetry during second stage of labor has a good correlation with umbilical artery pH at birth.