Ultrasound measurement of pregnancy-induced changes in maternal bone mass: a longitudinal, cross-sectional and biochemical study.

Our objective was to investigate the changes in maternal bone status in pregnancy. Amplitude-dependent speed of sound (AD-SoS) by quantitative ultrasound was measured in 100 healthy, White, pregnant women at term, and 100 White, healthy, non-pregnant and premenopausal women matched for age, as controls. In a subgroup of 50 women a longitudinal evaluation throughout pregnancy was performed. A significant reduction of AD-SoS was observed during pregnancy (controls: 2170 +/- 55 m/s; first trimester: 2118 +/- 46 m/s; second trimester: 2085 +/- 49 m/s; third trimester: 2081 +/- 51 m/s), showing a negative correlation with body mass index (r -0.31; p < 0.05) and a positive correlation with daily calcium intake (r 0.33; p < 0.05). Increased levels of urinary markers of bone resorption confirmed bone turnover (p < 0.05). Ultrasonographic study of bone is a simple, low-cost and safe method for measuring maternal bone mass in pregnancy. During pregnancy, there was a significant loss in AD-SoS that is an indicator of bone status; this decrease was higher in the second and third trimesters (p < 0.05), associated with a high bone turnover. It was more intense in women with a low calcium intake (p < 0.05).