RESUMEN
Cases past term were investigated for postmaturity by combined antenatal roentgenography and vaginal cytology. Postmaturity in infants was confirmed by postnatal roentgenography of the knee and foot for upper tibia and cuboid ossification centres.No diagnostic cellular pattern was found peculiar to postmaturity alone. A positive correlation was obtained between increasing pyknotic cell percentage and placental insufficiency reflected by increasing foetal distress and a fall in birth weight above a pyknotic cell percentage of 5 per cent in vaginal smears. An 85 per cent correlation was obtained between antenatal radiography and sub- sequent postnatal confirmation of postmaturity of the foetus. False positives and false negatives were equally distributed.The foetal mortality was nil, and it is felt that timely induction and Caesarian section were responsible for this. Vaginal cytology offers a useful ancillary diagnostic weapon in placental insufficiency associated with postmaturity and can also be used in other obstetrical conditions associated with placental insufficiency such as antenatal hypertension preeclampsia.