Salivary calcium, magnesium, phosphate, chloride, sodium and potassium in pregnancy and labour.

Pregnancy and labour produce significant changes in salivary calcium, magnesium, phosphate and chloride when pregnant patients in labour are compared with non-pregnant patients. There is a decrease in concentration of these constituents in the 3rd trimester of pregnancy followed by a marked increase when labour occurs. Magnesium and chloride are the constituents most significantly affected and show the largest increase during labour. Changes in saliva flow rate were accounted for and are not responsible for these changes noted. Sodium and potassium follow a similar pattern. When their levels are corrected for saliva flow rate changes, both show a significant increase with the onset of labour.