What's the worry about anaemia?
How can I raise my iron levels?
Does a low Hb count mean you're more likely to haemorrhage?
Is the problem really iron deficiency?
Arranging a homebirth when you have low Hb
Sometimes women with haemoglobin (Hb) levels below a certain level are advised not to have a home birth. Mayes' Midwifery textbook says:
"The World Health Organization (1979) considers anaemia to be present in the pregnant woman when haemoglobin is 11g/dl or less. More arbitrary levels may be decided locally and usually range between 10 and 10.5g/dl"
In the UK, the most common definition of mild anaemia is an Hb level of 10 g/dl (100g per litre of blood) or less. Severe anaemia is usually defined internationally as 7g/dl (70g/L) or less, but to complicate matters, some studies define this as 'moderate' anaemia, and 'severe' as 4.7g/dll or less.
Severe anaemia is a major problem in the developing world and it increases the risk that a baby will be born prematurely, or have a low birthweight. The risks are highest when the mother is anaemic in the first trimester of pregnancy as this suggests that her nutritional status before pregnancy was poor - her low Hb levels cannot be caused by her blood volume expanding ('haemodilution of pregnancy') because blood volume will not have expanded greatly at this stage. If a woman is anaemic in the first trimester because of poor nutrition, it may also suggest that she will not have a good diet or healthcare during her pregnancy. Many women in the developing world who suffer from anaemia may not simply be deficient in iron, but may also have malaria, sickle-cell anaemia or other blood diseases ('haemoglobinopathies') and some of the research into anaemia in pregnancy looks at different categories individually. However, you will occasionally see attention-grabbing quotes saying that women with anaemia have significantly higher rates of stillbirth. Where references are given, it often turns out that the source is a study looking at severely anaemic women in the developing world - not necessarily relevant to a woman in the UK with only mild anaemia.
There seems to be no good evidence that a woman in the developed world with an Hb level of 9 or 10, and no other complicating factors, is at any increased risk of complications in labour, nor her baby at increased risk after birth. For instance, in a study of Swedish women, Stephansson (2000)found that anaemia was not significantly associated with risk of stillbirth in multivariate analyses, although high haemoglobin (146 g/l or more) was associated with an increased risk of stillbirth. Several studies have now found that the best outcome for the baby, in terms of avoiding low birthweight and prematurity, arises when the mother is actually mildly anaemic by standard definitions. For instance, Malhotra et al (2002) compared outcomes for women with 'normal' blood (Hb above 11g/dll) with those for women with mild anaemia (9 - 10.9 g/dll), moderate and severe anaemia (severe being Hb lower than 7g/dll). They found that:
"Women in Group II (milkd anaemia) had lowest number of low birth weight and IUGR babies, no stillbirths and neonatal deaths, lowest induction and operative delivery rates. ... Mild anemia fared best in maternal and perinatal outcome. Severe anemia was associated with increased low birth weight babies, induction rates, operative deliveries and prolonged labor."
Sometimes it is suggested that if the mother is anaemic, she may be more likely to have a post-partum haemorrhage (PPH). However, there appears to be no evidence that this is true; the topic is discussed further below. Very low Hb levels may be symptoms of an underlying health problem which may affect your choice. The main risk of slightly low haemoglobin levels is that you will feel more tired than usual in pregnancy, and that if you had a large bleed, your recovery might be more difficult. In fact, as you are less likely to suffer a haemorrhage at a homebirth (because of reduced intervention levels - see Postpartum Haemorrhage and Homebirth), the woman with anaemia may stand more to gain from a homebirth than the woman with higher iron stores. You can still plan a homebirth, regardless of your iron count - but read on for issues to consider.
Many health authorities have a 'guideline' that they recommend hospital birth with an Hb level of below 10g/dLL. It's important to be aware that this is just a guideline - it's *advice* and the point about advice is that you can consider it, and then decide whether to take it or not. It's a one-size-fits-all guideline and has no status in law.
It's useful to find out if your blood test results included a full blood count. In particular, what was your mean cell volume (MCV)? This is a measure of how 'fat' or 'skinny' your red blood cells are, ie whether they really are deprived of iron or not. Sometimes 'anaemia' is just good haemodilution, ie your blood volume has expanded a lot, but you aren't actually short of iron - your blood just is just more 'dilute'. If this is the case then your MCV would be fine. Normal MCV levels are around 80-100, although there is some variation in definitions of 'normal'.
Here's an extract from the NHS patient information database:
http://www.patient.co.uk/showdoc/40000289/
Investigations Hb < 11.0g/dl 3
MCV (mean cell volume): if < 76fl then probable cause is iron deficiency but if lower than concomitant with other signs of anaemia and RBC count raised, then suggests possible ß-thalassaemia (estimate HbA2 and use Hb electrophoresis).
Normal MCV (76-96fl) with low Hb is typical of pregnancy.
There are other reasons for anaemia besides iron deficiency, and some of them might have other implications for your health - your midwife would probably already have considered these possibilities. Nonetheless it's worth checking - if you find out your Hb level and MCV, and your MCV is normal, then you could ask your midwife why she thinks you are iron-deficient, or indeed higher-risk in any way.
"A Guide to Effective Care in Pregnancy & Childbirth (2nd Edition) " by Enkin, Keirse, Renfrew and Neilson, is the UK's 'gold-standard' textbook on evidence-based maternity care and is generally respected by all midwives and obstetricians. Here's what it says on this subject:
The normal haematological adaptations to pregnancy are frequently misinterpreted as evidence of iron deficiency that needs correcting. Iron supplements have been given with two objectives in view: to try to return the haematological values towards the normal non-pregnant state, a strange objective when millions of years of evolution have determined otherwise, and to improve the clinical outcome of the pregnancy and the future health of the mother. The first objective can certainly be accomplished; the key question is whether or not achieving the "normalized" blood picture benefits the woman and her baby. Routine iron supplementation raises and maintains serum ferritin above 10 microgram/litre and results in a substantially lower proportion of women with a haemoglobin level below 10 or 10.5 grams per cent (below 6-6.5 mmol/litre) in late pregnancy. Routine folate supplementation as a haematinic after the first few weeks of pregnancy substantially reduces the prevalence of low serum and red cell folate levels, and of megaloblastic haematopoiesis.
As yet, neither iron nor folate supplementation after the first trimester have shown any detected effect on the following substantive measures of maternal or fetal outcome: proteinuric hypertension, antepartum haemorrhage, postpartum haemorrhage, maternal infection, preterm birth, low birthweight, stillbirth, or neonatal morbidity. Women do not feel any subjective benefit from having their haemoglobin concentration raised.
A possible advantage claimed for a high level of haemoglobin in pregnancy is that the woman would be in a stronger position to withstand haemorrhage. There is no evidence to support this claim. indeed, as a low haemoglobin in healthy pregnant women generally implies a large circulating blood volume, it is at least possible that women with a low haemoglobin might better withstand a loss of blood....
Whether routine iron supplementation causes any harm in well-nourished communities is still unclear, but it is clearly wasteful. The evidence suggests that, except for genuine anaemia, the best reproductive performance is associated with levels of haemoglobin that are traditionally regarded as pathologically low. There is cause for concern in the findings of two well-conducted trials that iron supplementation resulted in an increase in the prevalence of preterm birth and low birthweight. Perhaps there is an adverse effect on fetal growth due to the increased viscosity of maternal blood that follows the iron-induced marcrocytosis and increased haemoglobin concentration, which may impeded uteroplacental blood flow.
An individual's haemoglobin concentration depends much more on the complex relation between red-cell mas and plasma volume than on deficiencies of iron or folates. The advent of electronic blood counters has given an opportunity for more appropriate criteria to be applied to the diagnosis of anaemia. Mean cell volume may be the most useful; it is not closely related to haemoglobin concentration and declines quite rapidly in the presence of iron deficiency. A low haemoglobin without other evidence of iron deficiency requires no treatment.
Lots of women have a diet which is plentiful in iron, but still for some reason do not absorb enough of it. If you are convinced that your iron level is genuinely low then it is worth taking action to increase it. Before you do this, however, please read 'Is the problem really iron deficiency?'. If you are not deficient in iron then the best-case scenario is that taking iron supplements will give you expensive wee; however, if you take prescribed iron supplements then you may well end up with unpleasant side-effects including nausea, constipation, etc..
Two iron supplements which are popular with pregnant woman are Floradix and Spatone. Both can be bought from health food stores like Holland and Barrett, and often from Boots, as well as from plenty of online retailers.
Spatone has a section on its website for health professionals which cites some impressive research showing that it is absorbed incredibly quickly into the bloodstream and is extremely effective at raising blood Hb levels. It's actually only a form of naturally iron-rich water - even tastes like rusty water.
The real bonus of this, and other forms of 'natural' iron like Floradix, is that they don't usually cause any gastric symptoms; the NHS iron supplements are cheap and nasty, and while they give you a massive whack of iron, it's in a form which is hard for your body to absorb. The unused portion can cause diahorrhea, constipation, nausea, you name it - which is why there is such a market for less offensive alternatives.
There are four studies on Medline of the effectiveness of Spatone and they all seem to confirm the manufacturer's claims, which you can find on the 'health professionals' section of its website (www.spatone.co.uk).
All iron supplements are most effective when taken with vitamin C as it helps absorption of iron (eg take in/with a glass of orange juice), and avoid tea as tannins hinder absorption.
I've trawled through Medline, the international database of medical research, and found nothing on correlations between low Hb antenatally and risk of haemorrhage. Not surprisingly, there are papers showing that a low postpartum Hb level is associated with having had a PPH. This is like saying that cars with dents are likely to have been involved in accidents than cars without dents. However, that does not mean that your car is more likely to be involved in a crash in future, just because it has a dent already!
The extract from 'A Guide to Effective Care in Pregnancy and Childbirth', above, explains that Hb levels in pregnant women are generally lower than in non-pregnant women, but that this does not mean that low Hb levels are a problem. Iron supplements can normally raise Hb levels in pregnant women to the 'normal' level for non-pregnant women, but there is no evidence that raising the Hb levels in this way benefits mother or baby at all.
I asked doctors and medical students on sci.med.obgyn newsgroup if there was any evidence that low Hb levels might increase the chances of post-partum haemorrhage. These were the responses:
I am studying obstetrics at the moment... I know of no evidence to this effect. The mechanisms of PPH are uterine atony, lacerations, and retained products. None of these should be affected by anaemia, though I guess a general aplasia of marrow could lead to thrombocytopenia as well as anaemia.
The reason why haemoglobin levels are low is because the plasma volume increases, while erythrocyte production doesn't increase so much. Hb levels are measured as a concentration, not as an absolute amount. Thus there is a normal 'anaemia' associated with pregnancy, which causes no problems. Of course one can also get folate/iron deficiency or malnutrition which causes a genuine anaemia.
Richard Cavell
This myth has been around a while...I've never seen any evidence...
It also depends on definition...if your definition of PPH is need for transfusion, then maybe it's true since if you start with a lower Hgb, you can suffer less blood loss before you need a transfusion. If your definition is strictly how much you bleed, then starting Hgb is irrelevant...
Adam Newman, MD
(Postpartum haemorrhage is defined in most countries as blood loss over 500mls, but some midwives and obstetricians prefer to look at the condition of the individual woman, and consider her blood loss to have been excessive if she is showing syptoms suggesting that, regardless of how much her measured blood loss is. While this is good for individualised care, it's not helpful if you want to collect data, make comparisons, and so on!)
It seems that it is probably irrelevant to 'risk out' a woman from home birth because of her Hb level. Such advice is probably due to an incorrect understanding of the implications of low Hb levels.
Some people suggest that, while the actual risk of haemorrhage doesn't increase when Hb levels are low, if a mother with low Hb does haemorrhage, she might find it harder to recover. This reflects the point made above by Dr Newman. However, there appears to be little evidence to support even this. For example, in the section from 'A Guide to Effective Care in Pregnancy & Childbirth' by Enkin, Keirse, Renfrew and Neilson copied below,
"A possible advantage claimed for a high level of haemoglobin in pregnancy is that the woman would be in a stronger position to withstand haemorrhage. There is no evidence to support this claim. Indeed, as a low haemoglobin in healthy pregnant women generally implies a large circulating blood volume, it is at least possible that women with a low haemoglobin might better withstand a loss of blood. "
Of course, any mother suffering a serious haemorrhage would be transported to hospital immediately, where she could receive a blood transfusion. Transfer times to hospital should be taken into account when making any decision about home birth, but when transfusions are given, it is often a day or more after the birth, rather than as an emergency measure.
This website has more information on Postpartum Haemorrhage and Homebirth - how likely it is, and what happens if you have a PPH at home.
If your midwife or doctor maintains that a low Hb level makes you an unsuitable candidate for home birth, please consider asking them for evidence and citations to support their claims. I would be very interested to hear of any research which backs it up. I've been looking for ten years now and nothing convincing has been forthcoming!
If you make an informed choice to continue with homebirth plans 'against advice' then it can be helpful to write a letter to the Head of Maternity or the Community Midwifery Manager at your hospital, copied to your community midwives. Here is a sample letter:
Dear Community Midwifery Manager,
I am booked for a home birth under the care of Team X, and my estimated due date is (date).
Midwife Z has informed me that your guideline is to recommend hospital birth whenever a woman's haemoglobin count is below 10 g/dLL, and my count at the last test was (result).
I am writing to inform you that I have looked into the matter and have decided to continue with my homebirth plans. I believe that the risks of hospital birth in my situation outweigh the benefits at the moment. If my circumstances change then I will of course consider the situation again. I appreciate the advice of my midwives, but I am prepared to take responsibility for my own decisions. I am informing you of my decision now so that you have plenty of time to make the necessary arrangements, to ensure that staff are available to attend my birth at home.
[If you want to, and fully understand the subject, you could add a paragraph here giving more details of your individual circumstances. You do not need to justify your decision to give birth at home, or to explain it, or to 'persuade' anyone to 'allow' you a homebirth. However, you may choose to discuss it further, both to make sure that you are fully informed, and perhaps to help your midwives be more open-minded with other women! If you show that you understand the subject it may reassure your midwives - they may be concerned that you might blame them if you went ahead with a homebirth, and, unlikely though it is, had a heavy bleed, and then needed to transfer to hospital afterwards. I believe it is important, if you want to get involved in a technical discussion, that you understand all the terms involved and feel confident using and discussing them. If you don't feel confident, it may be better to avoid using them!]So - the sort of thing you might add here could be:
I have been given the results of my full blood count and my Mean Cell Volume is 88. This is well within normal limits of 80-100 and therefore there is no reason to suppose that I am iron-deficient. There have been no abnormal results suggesting ill health of any kind. I believe that my Hb level of 9.5 g/dLL is accounted for by normal haemodilution of pregnancy and, following the guidelines in A Guide to Effective Care in Pregnancy and Childbirth, that I am not at any increased risk, nor in need of any treatment, as a result.
Yours faithfully,
Ms Stroppy
For more discussion of these issues, and suggestions of ways to raise your Hb levels through diet and supplements, see the Association of Radical Midwives archive on the Third Stage of Labour.
Merck medical manual - chapter on Anemia in Pregnancy
http://www.merck.com/mmpe/sec18/ch261/ch261b.html
Anaemia in Pregnancy - patient.co.uk information sheet
JAMA. 2000 Nov 22-29;284(20):2611-7.
Maternal hemoglobin concentration during pregnancy and risk of stillbirth.
Stephansson O, Dickman PW, Johansson A, Cnattingius S.
PMID: 11086368 [PubMed - indexed for MEDLINE]
Malhotra et al (2002):
Int J Gynaecol Obstet. 2002 Nov;79(2):93-100.
Maternal and perinatal outcome in varying degrees of anemia.
Malhotra M, Sharma JB, Batra S, Sharma S, Murthy NS, Arora R.
PMID: 12427391 [PubMed - indexed for MEDLINE]
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