Ultrasonographic bone characteristics during normal pregnancy: Longitudinal and cross-sectional evaluation

OBJECTIVE: We evaluated the pattern of bone density during pregnancy by radiation-free ultrasonographic densitometry. STUDY DESIGN: In a longitudinal study we measured bone mineral density in a group of 10 normal primiparous women, from the fourteenth to the thirty-eighth weeks of pregnancy. In a cross-sectional study bone mineral density was determined in a group of 85 normal primiparous women, in different weeks of pregnancy. RESULTS: In the longitudinal study ultrasonographic bone density was stable in the first part of pregnancy, whereas a significant (p< 0.05) decrease was evidenced during the third trimester. A negative correlation between bone density and weeks of pregnancy (p< 0.0001) was evidenced in the cross-sectional study. CONCLUSION: During physiologic pregnancy the calcium mobilization from the maternal bone stores to accomplish the fetal needs can cause a significant decrease in maternal bone density in the last trimester of gestation.