Letters

Placental transfusion might reduce prevalence of iron deficiency

There is evidence that relatively large volumes of blood are retained in the placenta after immediate or early clamping of the cord. The mean volume of cord blood collected from 132 placentas in one study was 117 ml (range 43-210)² and from 167 placentas in another study 112 ml (range 30-200).³ The average blood volume of term infants is 80-85 ml/kg, so these quantities represent a considerable proportion of the blood available for infants. In the second study the haemoglobin concentration was measured one day after delivery in 125 infants. When the collection of placental blood exceeded 100 ml the mean haemoglobin concentration was 156 g/l (range 122-192), and when the collection of placental blood was 80 ml or less the mean haemoglobin concentration was 175 g/l.³ These figures show the quantity of infant blood remaining in the placenta and its effect on neonatal haemoglobin concentrations. Standard texts quote normal mean haemoglobin concentrations on day 1 as being 190 g/l.⁴ As cord and day 1 haemoglobin concentrations are measures of iron stores available to the infant a reduction in the quantity of blood left in the placenta must increase the iron stores of the infant.

Iron deficiency in infancy is by no means confined to developing countries. A recent survey of diet and nutrition in Britain showed iron deficiency in 25% and iron deficiency anaemia in 12% of children from private households in the second year of life.⁵ There was no significant association between the haematological variables and social class or employment status. Moderate placental transfusion resulting from delay in clamping the cord might well reduce the prevalence of iron deficiency. We join with Pisacane in urging that a large clinical trial be undertaken to evaluate the effects of placental transfusion.

Associate specialist in haematology Consultant haematologist Belfast City Hospital, Belfast BT9 7AB

G Markey, T C M Morris 

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