A system is described for measuring amniotic fluid volume and/or assessing fetal weight. The system includes an ultrasound apparatus to scan a pregnant uterus and to generate data representative of a three-dimensional construction of the scanned uterus, and a processor to compute a volume of amniotic fluid or weight of fetal tissue based on the three-dimensional construction of the scanned uterus. Also a method of computing a volume of amniotic fluid and/or a weight of fetal tissue.