Types of anaemia

Anaemias can be classified according to their causes:

Effects on pregnancy and childbirth

Anaemia will have the following effects:

Signs and symptoms

Investigations

After taking a detailed history about general health, diet, infection, blood loss and other relevant information, further investigations such as haemoglobin level, mean corpuscular volume (MCV), packed cell volume (PCV), total iron binding capacity, and serum ferritin will give a full picture (McKay 2000, NICE 2008a) (see Ch. 33).

Management

Where iron deficiency anaemia has been diagnosed, oral iron 120–140 mg daily may be given as:

Women need to know that iron absorption is enhanced by vitamin C and inhibited by tannin in tea, and that there might be some side-effects, such as blackness of stools, nausea, epigastric pain, diarrhoea and constipation. Side-effects may be reduced by taking the iron after meals, although this decreases iron absorption. It may be better tolerated at bedtime, and by leaving 6 to 8 hours between doses. However, the type and dose may need to be changed if symptoms persist (Jordan 2002). This is also a good opportunity for the midwife to provide dietary advice (see Ch. 17).

In more severe cases of anaemia, the woman may be given intramuscular injections of iron. Special precautions should be taken when administering this, to avoid permanent staining of the skin (Jordan 2002).

Management

Dietary sources of folic acid are lightly cooked green leafy vegetables, such as broccoli and spinach (see Ch. 17). Following the demonstrated link between neural tube defects and intake of folic acid, all pregnant women, and those intending to become pregnant, are advised to take 0.4–4 mg folic acid daily (NICE 2006).

Sickle cell trait and sickle cell disease

In sickle cell disease, erythrocytes containing HbS have a short lifespan of 5–10 days (rather than the normal span of 120 days). ‘Sickling’ occurs when cells become sickle shaped under conditions of low oxygen tension, including hypoxia, dehydration, infection, acidosis and cold (Dike 2007, Nelson-Piercy 2006). Cells are easily haemolysed and cause extremely painful vaso-occlusive symptoms in joints, in the abdomen and in the extremities during acute exacerbations, known as a crisis. This leads to chronic haemolytic anaemia, and an increase in the rate of haemoglobin synthesis in the bone marrow, which may lead to folic acid deficiency. Other complications are thromboembolic disorders, retinopathy, renal papillary necrosis, leg ulcers, and increased risk of infection because of disorders in the function of the spleen (Dike 2007, Nelson-Piercy 2006). Acute chest syndrome may occur, in which there is pyrexia, tachypnoea, leucocytosis and pleuritic chest pain.

Management

Thalassaemia

Thalassaemia is a condition in which there is an abnormal amount of HbA₂. It is most common in people of Mediterranean and Asian origin. The condition arises from defects in the alpha or beta globin chains resulting in thin, shortly lived red cells, often misshapen and deficient in haemoglobin, causing profound anaemia. As with sickle cell trait, thalassaemia in its mild forms confers some protection against malaria.

Management

As iron stores are likely to be overloaded, rather than depleted, iron supplements are not usually given. Folic acid is given throughout pregnancy, however, because the bone marrow is active in replacing the short-lived red blood cells.

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency

This rare, X-linked inherited enzyme deficiency typically affects people of African, Asian and Mediterranean origin. Haemolytic crises occur if the affected person takes certain drugs, including antimalarial preparations, sulphonamides and antibiotics (nitrofurantoin, nalidixic acid and possibly chloramphenicol) or eats broad (fava) beans. It may be implicated in cases of prolonged neonatal jaundice.

Congenital heart disease

Congenital defects relate to the structure of the heart, and the most common are atrial septal defects, patent ductus arteriosus, and ventricular septal defects. Other more serious lesions include Fallot’s tetralogy (ventricular septal defect, pulmonary stenosis, overriding aorta and right ventricular hypertrophy) and Eisenmenger’s syndrome (ventricular septal defect, overriding aorta and right ventricular hypertrophy). Most lesions are corrected by surgery in childhood. Marfan’s syndrome is a genetic condition in which cardiac anomalies occur. Pregnancy outcome is worst where there is pulmonary hypertension in Eisenmenger’s syndrome and in Marfan’s syndrome where there is aortic involvement (Adamson et al 2007). Many pre-existing cardiac disorders are complex, and pre-pregnancy counselling is essential, so that women know their own health status in relation to likely outcome. Some women, particularly those with cyanotic heart disease and pulmonary hypertension, may be advised to avoid pregnancy, or, if pregnant, may be advised to have termination of pregnancy (Adamson et al 2007). However, the woman’s choice must be respected.

Acquired heart disease

This usually involves damage to heart valves, such as stenosis, where the valve is constricted, or incompetence, where the valve fails to close completely. Valvular problems are often subsequent to infection or rheumatic heart disease, now rare in the UK but prevalent in developing countries, and a problem for immigrant mothers (Lewis 2007). Women who have had valve replacements will be on anticoagulant therapy, and choices need to be made to balance the need for anticoagulants against the risks they pose for the fetus. Warfarin is teratogenic in early pregnancy and may lead to fetal haemorrhage at any time. There is considerable debate about appropriate combinations of warfarin and heparin and whether fetal risks may be reduced by changing to self-administered subcutaneous or intravenous heparin, which does not cross the placenta, after the first trimester (Adamson et al 2007). The effects of heparin are reversed by protamine sulphate.

Peripartum cardiomyopathy is a rare, functional, cardiac complication, with sudden cardiac failure, arising in the last month of pregnancy or in the first 5 months postpartum, where there has been no evidence of heart disease pre-pregnancy. It is more common in women of black race, multiparity, and higher maternal age, and is a significant cause of maternal mortality (Adamson et al 2007, Lewis 2007, McLean et al 2008).

Effects on the fetus in maternal cardiac disease

Antenatal care

Pre-pregnancy counselling and then care in a dedicated antenatal cardiac clinic are required, with input from obstetrician, cardiologist, anaesthetist and midwife (Adamson et al 2007).

Aims of antenatal care are to detect heart failure and disturbances of cardiac rhythm. Women and their partners need help and support during what may be a particularly anxious time. Practical help may be needed with housework, transport to clinics and childcare.

A high-protein, low-carbohydrate, low-salt diet is recommended. Weight control is important, as excessive weight gain places extra strain on the heart. Infection is treated with antibiotics to reduce the risk of bacterial endocarditis; dental work, which may be a potential source of infection, should be carried out early in pregnancy.

Major antenatal complications are acute pulmonary oedema and congestive cardiac failure. Women and partners should be aware of symptoms which indicate worsening of the condition, such as dyspnoea, cough or chest pain, which will need hospital admission immediately for stabilization.

Labour

Depending on the type of cardiac disorder and the progress of the pregnancy, labour may be spontaneous or induced or an elective caesarean section may be carried out. Prophylactic antibiotics may be given to reduce the risk of bacterial endocarditis (Adamson et al 2007). Epidural analgesia is recommended, but with caution in regard to hypotension, and it is contraindicated in women on anticoagulant therapy. The optimum position for the woman is the ‘cardiac position’ supported left lateral, or semi-upright, with the legs lower than the abdomen (Adamson et al 2007). In addition to usual midwifery observations in labour, the following are important:

In the absence of obstetric complications, vaginal delivery causes less haemodynamic fluctuation than caesarean section (Adamson et al 2007).

There is no reason for elective instrumental delivery if birth is proceeding well; however, excessive pushing should be avoided since it alters haemodynamics and may compromise cardiac activity. If the woman feels the urge to push, short pushes with the mouth open should be encouraged. Sudden strong uterine contraction in the third stage may direct so much of the uterine circulation of blood to the systemic circulation that the impaired heart may become seriously compromised, therefore ergometrine and syntometrine are not used. Syntocinon should be used with caution, and is contraindicated in cases of heart failure (Adamson et al 2007).

Postnatal care

Continuing close observation of vital signs is necessary as heart failure or peripartum cardiomyopathy may occur in the first few days postnatally. Women require rest, but not complete immobilization. Physiotherapy helps to reduce the risk of thromboembolic disorders. There is usually no contraindication to breastfeeding. The risk of congenital heart disease in the baby is increased and, therefore, careful examination of the baby is essential.

Careful plans should be made for transfer to the community. Women need practical help to enable them to rest, and cope with the demands of the baby. An appointment should be made with the cardiologist 4–6 weeks postnatally, to assess cardiac function. Advice should be given on appropriate contraception postnatally, and pre-conception counselling for future pregnancies.