Ga. Dildy et al., INTRAPARTUM FETAL PULSE OXIMETRY - FETAL OXYGEN-SATURATION TRENDS DURING LABOR AND RELATION TO DELIVERY OUTCOME, American journal of obstetrics and gynecology, 171(3), 1994, pp. 679-684
OBJECTIVES: Our purpose was to study fetal arterial oxygen saturation
trends by continuous pulse oximetry during labor in subjects with norm
al and abnormal delivery outcomes. STUDY DESIGN: Continuous fetal arte
rial oxygen saturation was measured during labor with a noninvasive re
flectance pulse oximeter designed for fetal application. Averaged arte
rial oxygen saturation values were compared between stage 1 and stage
2 of labor, with stage 1 further subdivided into early (less than or e
qual to 4 cm), middle (5 to 7 cm), and late (8 to 10 cm) phases. Deliv
ery outcome was considered to be abnormal for any of the following con
ditions: gestational age < 37 weeks, maternal oxygen administration, d
elivery by cesarean section, 5-minute Apgar score < 7, umbilical arter
y pH < 7.10, birth weight < 2500 gm, or newborn intensive care unit ad
mission. RESULTS: A total of 291 subjects were studied: 142 in Prove,
90 in Nijmegen and 59 in San Francisco. Subjects with delivery complic
ations (n = 125) were evaluated separately from those with normal deli
very outcomes (n = 160). Fetal arterial oxygen saturation was 58% +/-
10% (mean +/- SD) during the cumulative period of study for the normal
-outcome group. A significant decrease (paired t test, p < 0.001) in f
etal arterial oxygen saturation occurred from stage 1 (59% +/- 10%) to
stage 2 (53% +/- 10%) labor. When stage 1 was subdivided into early (
less than or equal to 4 cm), middle (5 to 7 cm), and late (8 to 10 cm)
phases, a gradual decreasing trend in fetal arterial oxygen saturatio
n was observed: 62% +/- 9%, 60% +/- 11%, and 58% +/- 10%. CONCLUSIONS:
With the use of reflectance pulse oximetry, a statistically significa
nt decrease in fetal arterial oxygen saturation was observed during la
bor in women with normal and abnormal delivery outcomes.