Oxygen Tension, Acid–Base Status and Electrolytes in Human Amniotic Fluid

Abstract

Determinations of oxygen tension, acid–base and electrolyte components in amniotic fluid were made in 199 cases of early pregnancy (gestational age 11–24 weeks) and in 107 cases of late pregnancy (gestational age 26–40 weeks). The values of Po₂, pH, sodium, chloride and osmolality decreased with advancing gestation, while those of Pco₂ and potassium increased. Bicarbonate values were higher in the 12th week than later on in pregnancy. The values of calcium and lactate were fairly constant. Total protein was higher in the 5th month than in the earlier and later periods of pregnancy. In late pregnancy the Po₂ values in amniotic fluid were positively correlated to maternal values of Pa_co2 and to base excess.