[ozmidwifery] measuring Hb during pregnancy

[Andrea Quanchi]

All this talk about haemaglobin reminded me about something I read recently and thought would make a good discussion.

I have just finished reading Michel O'Dent's book 'The Casarean' ( available from Birth International) which was very interesting reading. In it he discusses measuring Hb during pregnancy and I will type the relevent section from pages 115-116

He states that
'... there is a widespread belief that this test can effectively detect anaemia and iron deficiency. In fact this test cannot diagnose iron deficiency because the blood volume of pregnant women is supposed to increase dramatically, so the haemoglobin concentration indicates first the degree of blood dilution, an effect of placental activity. A large british study, involving more than 150,000 pregnancies found the highest average birth weight was in the group of women who had a haemaglobin concentration between 8.5 and 9.5. Furthermore when the haemaglobin concentration fails to fall below 10.5 there is an increased risk of low birth weight, pre term birth and pre-eclampsia. The regrettable consequence of routine evaluation of haemoglobin is that all over the world, millions of pregnant women are wrongly told that they are anaemic and are given iron supplements. there is a tendency both to overlook the side effects of iron (constipation, diarhhoea, heartburn etc) and to forget that iron inhibits the absorption of such an important growth factor as zinc. Furthermore, iron is an oxidative substance that can exacerbate the production of free radicals and might even increase the risk of pre-eclampsia. '

of course he gives references

Well I knew the first bit about blood dilution but was not aware of the study that showed the higher birth weight amongst the women with lower Hb or the tendancy to pre eclampsia to women with higher Hb. Makes sense though that if there is higher blood pressure then placental function/flow will be decreased and lead to lower foetal growth. Makes the whole thing a bit of a joke though doesnt it as Hb is the one thing I thought was worth knowing of the battery of tests that women are subjected to. Maybe we should be celebrating when there Hb comes back lower that 10.5 and 'worrying' when it doesn't. Cant you see it now new indication for keeping an eye on BP "Hb above 10.5'. Food for thought though. As it will make any though of supplements virtually obsolete.

Andrea Quanchi