There is no known health risks associated with pregnant woman using a TANITA body composition scale. Since research has not been done on this population extensively we advise women who are pregnant to use the TANITA scale for weight purposes only. This has to do with the fact that the results of the body measurement will not be accurate.
During pregnancy dynamic physiological changes occur, a pregnant woman cannot expect an accurate body fat and body water reading. The device cannot distinguish the embryo/fetus and the amniotic fluid, so the increased body weight will be translated to body fat and this will influence the rest of the results. Since obtaining an accurate reading during pregnancy is not possible, it would not be recommended to monitor your body composition until after delivery.