[Evaluation of quantitative ultrasonometry of bone in singleton and multiple pregnancies]

During pregnancy about 30 grams of calcium are transferred to a full-term neonate. The enormous demand for calcium can be regulated by compensatory mechanisms in the maternal metabolism such as elevated steroid hormone levels, increased intestinal absorption of dietary calcium, and renal conservation, but also by mobilization of calcium from the maternal skeleton. Therefore we have investigated whether a decrease in maternal bone mineral density (BMD) can be observed during pregnancy and whether it differs between singleton and twin pregnancies.

Quantitative ultrasonometry (QUS) was performed at the distal metaphysis of the phalanges (digits II - V). 54 singleton pregnancies and 6 twin pregnancies were longitudinally followed throughout pregnancy. In each trimester the amplitude-dependent speed of sound (AD-SOS) and the bone transmission time (BTT) were measured.

In 54 singleton pregnancies significant decreases in AD-SOS of 1.9 % (p

The results show that the compensatory mechanisms in maternal metabolism are not able to cover the fetal calcium demand and lead to a decrease in QUS parameters. In our pilot study due to the small number of twin pregnancies the decrease in QUS parameters did not reach statistical significance although the results seemed comparable to those of singleton pregnancies.