Fetal pulse oximetry Archives - Revista Brasileira de Ginecologia e Obstetrícia

Purpose: to study fetal oxygen saturation (SpO2) levels during labor by continuous pulse oximetry tecnique, and its relation to umbilical artery (UA) pH. Patients and Methods: fetal SpO2 levels were measured during labor by the pulse oximetry technique in 50 subjects. Average values of SpO2 were compared between the first and second stage of labor, with the first stage further subdivided into phases, according to cervical dilatation of (<=4 cm, 5-7 cm and 8-9 cm). SpO2 values were studied in relation to umbilical artery pH at birth ( > or = 7.20 and <7.20). SpO2 > or = 30.0% was considered normal. Results: fetal SpO2 averages during the first stage were 53.0 ± 7.3% and 44.2 ± 6.8% (UA pH > or = 7.20 and <7.20, respectively; p<0.01). When the first stage was subdivided, the fetal SpO2 averages (UA pH > or = 7.20) were 55.1 ± 5.1% (<=4 cm), 52.3 ± 4.6% (5-7 cm) and 51.5 ± 7.2% (8-9 cm); for UA pH <7.20, the fetal SpO2 averages were 46.3 ± 5.1% (<=4 cm), 43.6 ± 6.7% (5-7 cm) and 42.8 ± 5.8% (8-9 cm). Considering the UA pH, these differences were statistically significant (p<0.01). Conclusion: a significant decrease of oxygen saturation values was observed during labor when fetal pulse oximetry was used.

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.