Salivary estriol as an index to fetal wellbeing.

We adapted two commercially available kits for measuring serum estriol to use in assaying salivary estriol in the third trimester of pregnancy. Salivary estriol increases during gestation, as does unconjugated estriol in serum. With a meticulous collection protocol, fetal wellbeing can be monitored as successfully with saliva samples as with serum. A fetal demise was charted similarly by the salivary and the serum estriol assay. Inter- and intra-assay reproducibility (CV) of the saliva assay was 6.2%. Day-to-day CV, based on a fasting sample before breakfast but obtained 1 to 3 h after rising, was 14.8% (SD 5.8%). Values for salivary estriol obtained immediately after ingestion of food or drink dropped by 19.0% (SD 17.9%) and 32.1% (SD 21.9%), respectively, as compared with values determined immediately before intake of food or water.