Serum Calcium, Phosphorous and Alkaline Phosphatase levels in Different Trimesters of pregnancy

Fetus skeleton is formed during pregnancy and calcium and phosphorous for this mineralization is provided by mother, so significant changes may occur in the mother’s skeleton. This study was conducted to evaluate the changes of serum and urinary markers of ossification and bone absorption during pregnancy. In this cross-sectional study, from Oct. 2005 to Jul. 2006, 307 pregnant women, at Imam Reza Hospital in Mashhad, were randomly assessed. Serum calcium, phosphorous, ALP, 24 hours urinary excretion of calcium and phosphorus were determined. Data were analyzed by SPSS 9.5 software, ANOVA and Tukey HSD tests. ANOVA test indicated that, there was no significant difference between dependent variables (calcium, phosphorous, alkaline phosphatase), 24 hours urinary excretion of calcium, phosphorous and the age of mother (P=0.057), but there was meaningful relationship between serum ALP level, 24 hours urinary excretion of phosphorous and different trimesters of pregnancy (P=0.007). Serum ALP level in the third trimester was varied, compared to the first and second trimesters. However there was no difference in these amounts in the first and the second trimesters. There was no significant alteration in the mean ratio of serum calcium, phosphorus level and 24 hours urinary excretion of calcium in different trimesters of pregnancy (P= 0.070). Noticeable correlation observed between mean serum ALP, 24 hours urinary excretion of phosphorous and different trimesters of pregnancy (P= 0.007, P= 0.025 respectively). Also, differences in the mean serum calcium level, 24 hours urinary excretion of phosphorous in multiparous and nulliparous patientswas very clear.