The morphology of the placental bed in idiopathic sporadic and recurrent miscarriages was studied and the findings correlated with the fetal chromosomal pattern where possible. Defective development of haemochorial placentation, which was not necessarily linked with fetal chromosomal abnormality, was seen in association with some miscarriages. These preliminary results, not previously demonstrated, strongly support the concept that miscarriages and pregnancies complicated by pre‐eclampsia and/or small‐for‐gestational‐age infants may be a continuum of disorders with a similar pathology in the placental bed.