Clinical Practice Guidelines Antenatal Care — Module II
Considerations before testing
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- Considerations after a positive test result
- Testing in rural and remote areas
- Prevalence of iron, folate and vitamin B 12 deficiency during pregnancy
- Risks associated with iron, folate and vitamin B 12 deficiency during pregnancy
- Assessing haemoglobin concentration
- Further investigations
- Treating iron-deficiency anaemia
- Practice summary: anaemia
8.1Considerations before testingBefore tests are carried out, it is essential that: women are informed that it is their choice to have tests; women are able to give informed consent — verbal discussion should cover the reasons for testing, harms and benefits and associated treatments and be supported by appropriate resources (eg written materials, audio or video) and efforts should be made to ensure that women have understood the information they are given; women have opportunities to ask questions about tests and treatments; women are reassured that test results remain confidential (unless the condition is notifiable); discussions about consent are documented by the health professional involved; women who decline testing are offered the opportunity to discuss any concerns they may have without being coerced to reconsider the test; and there are processes for follow-up of women with a positive test result, their babies and, in some situations, partners. Discussion of testing should be approached with sensitivity, particularly when there is a potential for testing to raise maternal anxiety or if testing is for a sexually transmitted infection. Considerations after a positive test resultReferral for specialist care: For some conditions, such as haemoglobin disorders and thyroid dysfunction, specialist involvement will be required. Psychosocial support: Diagnosis of a condition that may affect pregnancy and/or the health of the baby can be distressing, particularly if there are no interventions that can change outcomes. Women should be given information about available supports and assisted to access these. Sexually transmitted infections: If a sexually transmitted infection is identified, there is an increased risk of other sexually transmitted infections. Testing and treatment of sexually transmitted infections and contract tracing have public health benefits as transmission to partners is reduced. Blood-borne infections: Specific supports are likely to be required for women identified as using intravenous drugs. Notification: State/Territory legislation on notification of communicable diseases must be followed. Type of testThe tests discussed in this section are those currently in use in Australia. With continuous advances in technology and testing, techniques change rapidly. The most appropriate test may also depend on the particular clinical setting. Testing in rural and remote areasIt is acknowledged that in Australia, access to tests may vary (eg due to distance from pathology services), storing tests and samples appropriately may be challenging (eg due to high temperatures or humidity) and there may be difficulties in recalling women to receive test results. In these situations, resources should be focused on responding to local needs (eg ensuring that tests are available to identify highly prevalent conditions). 8.2AnaemiaAntenatal care provides an opportunity to identify women with possible anaemia. If anaemia is diagnosed, supplementation with the deficient nutrient (most commonly iron) may be advised where indicated. BackgroundAnaemia is a lower than normal concentration of haemoglobin or number of red blood cells, which results in reduced capacity of the blood to carry oxygen. During pregnancy, the WHO criteria for mean minimum normal haemoglobin concentration in healthy pregnant women is 110 mg/dL in the first half of pregnancy and 105 mg/dL in the second. Iron deficiency is the most common cause of anaemia in pregnancy worldwide (WHO 2001), but other deficiencies may also cause anaemia: iron deficiency: demand for iron is increased during pregnancy (NPS 2010) and insufficient iron intake or absorption (eg diet poor in iron-rich foods and/or rich in foods that diminish iron absorption) or blood loss (eg due to gastrointestinal parasites) (ACOG 2008) can result in microcytic anaemia; folate deficiency: demand for folate is also increased during pregnancy and inadequate dietary intake, prolonged vomiting or impaired absorption (eg due to gastric bypass surgery or gastrointestinal conditions) can result in macrocytic anaemia; vitamin B12 deficiency: prolonged inadequate intake (eg limited access to source foods or vegetarian diet) or impaired absorption (eg due to gastric bypass surgery, pernicious anaemia or gastrointestinal conditions) can result in macrocytic anaemia; and haemoglobinopathies: these include sickle cell anaemia and thalassaemia (see Section 8.5). Symptoms of anaemia include general weakness and tiredness but the threshold concentrations of haemoglobin at which these symptoms occur in pregnancy is not known (Reveiz et al 2011). Prevalence of iron, folate and vitamin B12 deficiency during pregnancyRecent estimates report that one-quarter of the world’s population has anaemia. The burden of anaemia is considerably higher among indigenous populations compared to the general population (Khambalia et al 2011). The prevalence of iron-deficiency anaemia during pregnancy is generally low (< 20%) in developed countries (van den Broek 2003) and higher (35–75%) in developing countries (Africa, Asia, South America) (van den Broek 2003; Kalaivani 2009) and areas of socioeconomic disadvantage (USPSTF 2006). Reported predictors for having anaemia by 32 weeks gestation include young maternal age, non-white ethnic origin and increasing parity (Barroso et al 2011). Few studies have reported the prevalence of iron-deficiency anaemia during pregnancy in Australia. Iron-deficiency anaemia was identified in 18% of pregnant women in a Tasmanian study (n=2,654) (Khalafallah et al 2010) and in 11% of pregnant women in a South Australian study (n=430) (Zhou et al 2006). Data from Queensland suggest higher prevalence of iron-deficiency anaemia during pregnancy among Aboriginal than non-Indigenous women (Wills & Coory 2008). Smaller studies have found a prevalence of anaemia during pregnancy among Aboriginal women of 50% in remote Northern Territory communities (Bar-Zeev et al in press), 12% across 34 Aboriginal community health services (range 3–22%) (n=535) (Rumbold et al 2011) and 10% in Brisbane (n=1,523) (Stapleton et al 2011). Data from Western Australia and South Australia show higher prevalence of iron-deficiency anaemia during pregnancy among adolescent (14%) than adult women (6%) and among Aboriginal (23–25%) compared with non-Indigenous (8–10%) adolescent women (Westernberg et al 2002; Lewis et al 2009). Mandatory fortification of flour with folic acid has reduced the prevalence of low folate levels among Australian women of childbearing age (0.16% in 2010) (Brown et al 2011). A Western Australian study found low folate levels in 10% of Aboriginal women before flour fortification (Maxwell et al 2012). Vitamin B12 deficiency is common in most of the developing world (Stabler & Allen 2004; Allen 2009). Few studies have examined the prevalence of vitamin B deficiency in Australia (Flood et al 2006). However, there is emerging evidence of vitamin B12 deficiency among refugees due to limited or no sources of animal foods before resettlement (Benson et al 2010; Benson et al 2013). Preventing iron deficiency (through inclusion of iron-rich foods in the diet and/or iron supplementation) is discussed in Section . Risks associated with iron, folate and vitamin B12 deficiency during pregnancySevere iron-deficiency anaemia (haemoglobin concentration <70 mg/dL) can cause cardiac failure, (Lops 1995; WHO 1992; Williams & Wheby 1992) and reduce tolerance of blood loss associated with birth. It is unclear whether mild to moderate anaemia is associated with poor outcomes (Reveiz et al 2011). Deficiencies of folate (De-Regil et al 2011) or vitamin B12 (Molloy et al 2008) during pregnancy are associated with neural tube defects. Screening for anaemiaRoutinely offering a full blood count early in pregnancy and at 28 weeks is recommended in the United Kingdom (NICE 2008) and in Australia (RANZCOG 2009). Initial haemoglobin concentration is usually assessed in the context of this full blood count. Assessing haemoglobin concentrationDuring pregnancy maternal red cell mass and plasma volume increase and the haemoglobin concentration is reduced (NICE 2008). Haemoglobin is therefore checked against gestation-related thresholds. Table 8 : Assessing haemoglobin concentration during pregnancy
Source: WHO (1993). Consensus-based recommendation x Routinely offer testing for haemoglobin concentration to pregnant women early in pregnancy (at the first visit) and at 28 weeks gestation. Practice point r In areas where prevalence of iron-deficiency anaemia is high consider testing ferritin at the first antenatal visit. Further investigationsHaemoglobin concentration is not sensitive enough to be the sole means of diagnosing anaemia. Diagnostic tests include: full blood count (if this has not already been conducted); serum ferritin, which is the most sensitive single screening test to detect adequate iron stores (90% sensitivity at a cut-off of 30 g/litre) (Breymann 2002); and specific tests for folate and vitamin B12, if mean cell volume is high. Practice point s Further investigation is required for women with a low haemoglobin concentration for their gestational stage. Repeat screening at 36 weeks may also be required for women who have symptoms or risk factors for anaemia or who live in or have come from an area of high prevalence. Treating iron-deficiency anaemiaSummary of the evidenceEffectiveness and safety of treatments for iron-deficiency anaemiaThe evidence on treatments for iron-deficiency anaemia covers a very wide range of supplements, doses and routes of administration and focuses on changes in maternal haemoglobin concentration. Iron supplementation improves maternal haemoglobin concentrations, but there is a lack of evidence about the overall benefits of treating mild iron-deficiency anaemia in pregnancy (Reveiz et al 2012). Oral iron can cause gastrointestinal adverse effects (eg nausea, constipation) (Reveiz et al 2012). Intramuscular or intravenous iron is more effective than oral iron, but may have adverse effects (venous thrombosis and allergic reactions for intravenous treatment and pain, discolouration and allergic reactions for intramuscular treatment) (Reveiz et al 2012). Iron as part of general nutritional supplementation is discussed in Section 10.4 of Module 1. Given the lack of evidence on outcomes, the recommendation is not to routinely offer iron supplementation to women during pregnancy. Recommendation 19 Grade B Advise iron supplementation for women identified as having iron-deficiency anaemia. Practice point t Oral iron remains first-line treatment for iron-deficiency anaemia identified in the antenatal period. Intravenous iron should be offered to women who do not respond to oral iron or are unable to comply with therapy. In some remote settings, intramuscular iron may be administered by a health professional who does not have intravenous endorsement or where intravenous iron cannot be accessed. Dose of supplementationRecent studies provide high-level evidence on lower doses of iron supplementation. Iron supplements that are low dose (eg 20 mg) or taken less often than daily appear to be effective in treating anaemia in pregnancy with fewer gastrointestinal side effects compared with high-dose (eg 80 mg) or daily supplements (de Souza et al 2004; Sharma et al 2004; Zhou et al 2009; Reveiz et al 2012). Recommendation 20 Grade B Advise women with iron-deficiency anaemia that low-dose iron supplementation is as effective as high dose, with fewer side effects.
Other considerationsTreatment for hookworm infestation should also be considered in areas of high prevalence. Discussing anaemiaWhen haemoglobin concentration is low, points for discussion include: while anaemia in pregnancy is most commonly associated with iron deficiency, deficiencies of folate or vitamin B12 also result in anaemia and further tests are required to identify the cause; if a deficiency is identified, supplementation with the appropriate nutrient can correct the deficiency; supplements can be combined with foods rich in the relevant nutrient: iron-rich foods include meat, seafood and poultry; including a vitamin C rich fruit or vegetable in each meal and limiting tea and coffee to between meals aids absorption (Marsh et al 2009); foods rich in folate include fortified bread and cereals, dried beans and peas, dark green vegetables and citrus fruit and juice; and foods that contain vitamin B12 include meat, eggs, milk and cheese.
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