Fetal acidosis and hyperlacticaemia diagnosed by cordocentesis in pregnancies complicated by maternal diabetes mellitus.

Fetal blood samples were obtained by cordocentesis (ultrasound guided needle aspiration) from 28 pregnant Type 1 diabetic women between 20 and 40 weeks' gestation. Analysis of the deviations from normal values of blood pH and plasma lactate showed significant acidosis (p less than 0.001) and hyperlacticaemia (p less than 0.01) in the third trimester, but not in the second trimester. Blood PO2 and PCO2 levels did not differ significantly from normal values. The pH showed significant correlations with PO2 (r = 0.54; p less than 0.01) PCO2 (r = -0.70; p less than 0.001), lactate (r = -0.46; p less than 0.05), fetal glycosylated haemoglobin (r = -0.53; p less than 0.01), and maternal glycosylated haemoglobin (r = -0.57; p less than 0.01). Plasma lactate showed significant correlations with PO2 (r = -0.54; p less than 0.01), PCO2 (r = 0.50; p less than 0.05), and pH (r = -0.46; p less than 0.05). Neither pH nor lactate showed significant correlations with birthweight. These observations suggest that some fetuses of diabetic women are significantly acidotic and hyperlacticaemic in the third trimester. This may provide a possible explanation for the phenomenon of late intrauterine fetal death in pregnancies complicated by maternal diabetes mellitus.