A comparison of saliva, plasma unconjugated and plasma total oestriol levels throughout normal pregnancy.

Saliva unconjugated, plasma unconjugated and plasma total oestriol (E3) levels were measured longitudinally, by radioimmunoassay, in 25 normal women from 13 weeks gestation until delivery. The increase in salivary unconjugated oestriol closely paralleled that of plasma unconjugated oestriol and to a lesser extent that of plasma total oestriol. In each patient the percentage value of salivary E3/plasma unconjugated E3 x 100 was virtually constant throughout pregnancy but this percentage varied from one patient to another (mean 14.4%). The overall correlation coefficient (r) for salivary and plasma unconjugated E3 was 0.90. The variability in salivary levels in samples collected at daily, hourly, 15 min and 5 min intervals (12.7, 13.4, 10.1 and 9.3%) was similar to that previously described for plasma unconjugated E3. There was no distinct pattern in diurnal variation. It seems probable that measurement of salivary E3 could adequately replace that of plasma unconjugated E3 in the assessment of fetoplacental function.