BMJ 1995;310:1601 (17 June)

Letters

Study's conclusions are implausible

EDITOR,--I note that Philip Steer and colleagues used the word association to describe the relation they found between haemoglobin concentration and birth weight.1 In their discussion, however, they suggested that haemoglobin concentration might be a determinant of birth weight. I refer, for example, to the statement: "There is a theoretical risk that increasing haemoglobin concentration might actually reduce birth weight and do harm," albeit that they do not claim that there is consistent evidence.

I am interested that Steer and colleagues thought causality in that direction was the most likely explanation. Would not a more plausible explanation be that a large fetus will have a greater iron requirement and therefore cause anaemia in the mother? And that, conversely, a small fetus will be less demanding on the mother's iron stores? Also, the fetus is not the only player here. Another important consideration is the effect that a low haemoglobin concentration . . . [Full text of this article]


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Relevant Article

Relation between maternal haemoglobin concentration and birth weight in different ethnic groups
Philip Steer, M Ash Alam, Jane Wadsworth, and Anne Welch
BMJ 1995 310: 489-491. [Abstract] [Full Text]

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