While BIA scanning can safely be undertaken during pregnancy, we recommend women do not scan during pregnancy simply because a woman will experience a large amount of change in body composition over the course of the 40 week pregnancy, simply by nature of the baby’s development over that period. Maternal weight gain in pregnancy is widely considered necessary for an adequate foetal development and development rates of the baby will vary considerably over each trimester of the pregnancy and the increase of maternal weight will depend on changes of various anatomical feto-maternal structures (foetus, uterus, amniotic fluid, amniotic membranes, placenta), maternal body fat and breast tissue as well as total body water (TBW). TBW increases during pregnancy by about 5–8 litres and the composition of lean tissue changes as pregnancy progresses, thereby compromising the ability to obtain an accurate estimate of pregravid weight status and/or body composition immediately before or early in pregnancy and affecting the validity of body composition change estimates. Accordingly we recommend women refrain from BIA scans during pregnancy.