The placenta is essential for normal fetal development. Failure of the placenta can result in many fetal conditions, for example, intrauterine growth retardation (IUGR). Placentas from pregnancies complicated by IUGR show vascular damage, which may lead to the onset of pregnancy-induced maternal hypertension. Accurate placental assessment may, therefore, indicate which fetuses are at risk of IUGR and so improve clinical evaluation and management of both the fetus and the mother. Placental development and function can be assessed by a number of methods, including measurement of placental weight at mid-gestation (placental growth in the second trimester correlates strongly with placental weight at birth), assessment of fetal and placental circulation (an association between perinatal morbidity and abnormal blood velocity profiles has been established) and assessment of placental metabolism and nutritional transfer (a reduction in transfer of nutrients may be an early indicator of IUGR.