From Dr Odent
"My haemoglobin is now 11.4 in week of gestation 19. A friend of mine has 7.8. Do I have to take ferrum? Is there a haemoglobin-limit?
It is probable that from now on your hemoglobin concentration will decrease. The placenta - which is 'the advocate of the baby' - will send you hormonal messages so that you dilute your blood in order to make it more fluid. Your blood volume will increase dramatically (up to 40% to 50%). Although you'll still have the same amount of hemoglobin available, its concentration in your blood will be lower if the placenta is working well. The most authoritative published study on this issue involved more than 150 000 thousands births (Steer P, Alam MA, Wadsworth J, Welch A. Relation between maternal haemoglobin concentration and birth weight in different ethnic groups. BMJ 1995; 310: 389-91). According to this huge study a hemoglobin concentration between 8.5 and 9.5 during the second half of a pregnancy is associated with the best possible birth outcomes. Furthermore, when the hemoglobin concentration fails to fall below 10.5 there is an increased risk of low birth weight, premature birth and pre-eclampsia.
The regrettable consequence of misinterpreting this test is that, all over the world, millions of pregnant women are wrongly told that they are anemic and are given iron supplements. There is a tendency both to overlook the side effects of iron (constipation, diarrhea, heartburn, etc.) and to forget that iron inhibits the absorption of such an important growth factor as zinc. Furthermore, iron is a powerful oxidative substance that can exacerbate the production of free radicals. The disease pre-eclampsia is associated with an 'oxidative stress'. Pregnant women need antioxidants (provided in particular by fruit and vegetable) rather than oxidative substances.
You should print the abstract of the study I mentioned (you'll find it via PubMed, for example) in order to be in a position to discuss with practitioners who might tell you that you are anemic and that you need iron supplements. Don't take iron supplements as long as your iron deficiency has not been proven by specific tests (ferritine in particular).
I cannot comment on the hemoglobin concentration of your friend, first because I don't know if she is at the beginning or at the end of her pregnancy, and also because data regarding her lifestyle and data provided by a clinical exam should prevail upon the results of one laboratory test; this test should probably be repeated and completed, according to the context."