Biochemical Changes in Salivary pH and Its Correlation to Hemoglobin Levels, Calcium and Phosphate Ion Concentrations among Pregnant Women, Tanzania: A Cross-Sectional Study

Background: Surveys in Tanzania show that pregnant women have a significant burden of oral disease, although there is still little literature on the variation of their intraoral electrolytes. The present study investigated changes in salivary calcium (Ca2+), phosphate (PO43−), and hydrogen (H) ions during pregnancy and the correlation between salivary pH and hemoglobin levels. Methodology: A cross-sectional study involved sixty (60) pregnant women stratified by trimester and twenty (20) non-pregnant women attending an antenatal clinic at Mnazi Mmoja Hospital. Consecutive sampling was used, saliva was collected, and electrolyte levels were measured. Gestation age was the independent variable, whereas saliva pH and calcium and phosphate ion concentrations and hemoglobin levels were the dependent variables. Results: A difference in calcium concentration (z = −3.145, p = 0.001) and salivary pH (t = −2.49, p = 0.014) was observed between pregnant and non-pregnant women. Kruskal–Wallis tests for saliva Ca2+ and PO43− and ANOVA for saliva pH revealed differences in concentrations of saliva Ca2+, PO43−, and pH levels between trimester groups (saliva Ca2+ (H = 9.91, df = 3, p = 0.019), saliva PO43− (H = 12.36, df = 3, p = 0.006), saliva pH (F (3.76) = (16.42); p < 0.001)). Pearson’s correlation tests showed no association between salivary pH and hemoglobin levels. Conclusions: Pregnancy is associated with a reduction in saliva pH and saliva calcium levels with a progressive increase in the magnitude of reduction from the first trimester to the third trimester. Saliva phosphate reduction was noticed during the third trimester only and saliva pH levels were independent of hemoglobin levels.