Neonatal prevention ofiron deficiencyBMJ 1996; 312 doi: http://dx.doi.org/10.1136/bmj.312.7024.136 (Published 20 January 1996) Cite this as: BMJ 1996;312:136
- Alfredo Pisacane
Placental transfusion is a cheap and physiological solution
Iron deficiency anaemia in childhood is common even in socially advantaged populations. Low birth weight, early consumption of cows' milk, fast growth rate, and poor dietary iron intake are considered the main risk factors.1 Iron enriched infant formula and cereals have been shown to be effective preventive measures.2 3 In developing countries, where iron deficiency anaemia is common and iron enriched formula and cereals are often not available, preventing iron deficiency is not easy: infants who enjoy prolonged and exclusive breast feeding have been found to have good iron status,4 but such breastfeeding is increasingly rare; and although medicinal iron is cheap, its use may be culturally unacceptable or difficult to implement. Moreover, dietary iron supplementation can be dangerous in settings where malaria and diarrhoeal infection are endemic2 5 and for children whose iron stores are adequate.6
Iron stores at birth show huge individual variations, which correlate with iron stores in the same individuals at 6, 9, and 12 months of age.7 This may explain why the iron status of some infants remains sufficient, even if they do not receive adequate daily iron. Dietary iron seems to represent only one of the factors that influence iron status in the first year of life,8 9 probably because iron absorption from formula and cereals is modest and is inhibited by many components of the diet such as polyphenols in fruit and vegetables. If high neonatal iron stores are associated with a good iron status in late infancy,7 how can we safely increase neonatal stores?
The merits of early or late clamping of the umbilical cord have been controversial for many years.10 According to Usher et al,11 the estimated volume of placental transfusion varies from 20% to 60% of the existing blood volume (54-160 ml) depending on the time of clamping and the position in which the infant is held before clamping.12 Linderkamp and colleagues estimated that the amount of placental transfusion is about 35 ml/kg of birth weight when term infants are kept at the level of the vaginal opening and the cord is clamped three minutes after birth.13 The same authors have recently investigated the effect of placing the neonate on the mother's abdomen and clamping the cord only once it stops pulsating (Leboyer delivery).14 They found that these babies had blood volumes 32% higher than babies whose cords were clamped immediately after birth. The packed cell volume in cord blood was not affected by placental transfusion, but after 2-4 hours it rose in the group of infants whose cord was clamped late, from 0.51 (SD 0.05) to 0.62 (0.06). This difference was statistically significant when compared with infants whose cords were clamped early.
A moderate placental transfusion as achieved in the Leboyer delivery does not significantly increase neonatal jaundice, nor does it incur detrimental haemodynamic changes,14 although occasional cases of circulatory overload from excessive placental transfusion have been reported.10 Moreover, a moderate transfusion of about 20-30 ml/kg endows about 30-50 mg of “extra” iron and can help prevent or delay depletion of iron stores during late infancy.
Recent research from Denmark favours this hypothesis.7 Studying 9 month old infants born in a hospital whose policy was to clamp the cord late, the researchers found serum ferritin values higher than those reported for infants from other European countries,15 16 17 whose cords were assumed to have been clamped immediately after birth. Higher neonatal iron stores associated with late cord clamping could be one explanation for this observation. The positive effects of delayed cord clamping could be even more clinically and economically important among infants in developing countries. For those children a moderate placental transfusion could represent a physiological and inexpensive means of increasing iron stores. At the same time, delayed cord clamping represents a change in routine practice that favours early contact between a mother and her newborn baby. An overview of randomised controlled trials found a statistically significant association between such early contact and subsequent prolonged breast feeding18; this could therefore represent another measure to prevent iron deficiency.
Immediate cord clamping is currently routine practice, but its widespread acceptance was not preceded by studies evaluating the effects of depriving neonates of a significant volume of blood. A large clinical trial to compare the short and long term effects of placental transfusion is needed.