Umbilical vein

Biology

Gestation

Arterial blood

Fetus

Biochemistry

Anesthesia

Hypoxemia

Venous blood

Genetics

In vitro

pCO2

Gestational age

Hypercapnia

Internal medicine

Obstetrics

Respiratory acidosis

Medicine

Chemistry

Umbilical artery

Acidosis

Metabolic acidosis

Pregnancy

American Journal of Obstetrics and Gynecology

The pH, PO2, PCO2, and lactate concentration were measured in umbilical blood samples obtained by cordocentesis from 208 appropriate-for-gestational-age and 196 small-for-gestational-age fetuses at 18 to 38 weeks' gestation. In the appropriate-to-gestational-age fetuses umbilical venous (n = 173) and arterial (n = 35) PO2 and pH decreased, and umbilical venous and arterial PCO2 increased with advancing gestation. Blood lactate concentration did not change. Compared with the appropriate-for-gestational-age fetuses, the small-for-gestational-age fetuses were hypoxemic, hypercapnic, hyperlacticemic, and acidotic. There was mixed respiratory and metabolic acidosis, and the decrease in pH was significantly correlated with both hypercapnia and hyperlacticemia. In the umbilical artery (n = 53) there was a significant linear correlation between the degree of hypoxemia and the degrees of hypercapnia or acidosis. In the umbilical vein (n = 143), the correlations between the degree of hypoxemia and the degrees of hypercapnia, hyperlacticemia, or acidosis were exponential.

Blood gases, pH, and lactate in appropriate- and small-for-gestational-age fetuses