Rationale and evidence

It is estimated that 41.8% of pregnant women worldwide are anaemic (177). At least half of this anaemia burden is assumed to be due to iron deficiency (178), with the rest due to other conditions such as folate, vitamin B12 or vitamin A deficiencies, chronic inflammation, parasitic infections and inherited disorders. A pregnant woman is considered to be anaemic if her haemoglobin concentration during the first and third trimester of gestation is lower than 110 g/l, at sea level.

Low haemoglobin concentrations indicative of moderate or severe anaemia during pregnancy have been associated with an increased risk of premature delivery, maternal and child mortality, and infectious diseases. Growth and development may also be affected, both in utero and in the long term. Conversely, haemoglobin concentrations greater than 130 g/l at sea level may also be associated with negative pregnancy outcomes such as premature delivery and low birth weight.

Interventions aimed at preventing iron deficiency and IDA in pregnancy include iron supplementation, fortification of staple foods with iron, health and nutrition education, control of parasitic infections, and improvements in sanitation. During pregnancy, women need to consume additional iron to ensure they have sufficient iron stores to prevent iron deficiency. Therefore, in most low-and middle-income countries, iron supplements are used extensively by pregnant women to prevent and correct iron deficiency and anaemia during gestation.

An existing Cochrane systematic review assessing the benefits and harms of iron supplementation in healthy pregnant women was updated to arrive at this recommendation (179). Overall, women taking daily iron supplements were less likely to have LBW babies compared with controls and the mean birth weight was 30.81 g greater for those infants whose mothers received iron during pregnancy. There was no significant effect on preterm birth or neonatal death.

Daily iron supplementation reduced the risk of maternal anaemia at term by 70% and iron deficiency at term by 57%, but it had no significant effect on the risk of infections during pregnancy.

Rationale and evidence

As mentioned in the previous section, iron requirements are increased during pregnancy to support maternal need and fetal growth. The use of daily iron and folic acid supplements throughout pregnancy has been the standard approach to cover this gap and in turn prevent and treat IDA. Despite its proven efficacy, the use of daily iron supplementation has been limited in some settings, possibly due to a lack of compliance because of common side-effects (e.g. nausea, constipation, dark stools or metallic taste), concerns about the safety of this intervention among women with an adequate iron intake, and variable availability of the supplements at community level.

Intermittent iron supplementation, that is, the provision of iron supplements once, twice or three times a week on non-consecutive days, has thus been proposed as an alternative to daily supplementation.

A Cochrane systematic review (182) assessing the benefits and harms of intermittent supplements of iron alone or in combination with folic acid or other vitamins and minerals in pregnant women on neonatal and pregnancy outcomes found that there was no detectable difference between women taking iron supplements intermittently and those receiving daily supplements with regard to maternal anaemia at term, the risk of having a low–birth-weight or preterm baby or mortality.

Fewer side-effects were reported in women receiving intermittent rather than daily iron and folic acid supplements. High haemoglobin concentrations (more than 130 g/l) during the second and third trimester of pregnancy were also less frequent among women using supplements intermittently. The intervention seems to be equally effective among populations with different prevalences of anaemia, and in settings described as malaria endemic, and regardless of whether the supplementation was initiated earlier or later than 20 weeks of gestation or whether the dose of elemental iron per week was lower or higher than 120 mg.

If a woman is diagnosed with anaemia at any time during pregnancy, she should be given daily iron (120 mg of elemental iron) and folic acid (400 μg or 0.4 mg) until her haemoglobin concentration rises to normal. She can then switch to the standard antenatal dose to prevent recurrence of anaemia.

Actions to promote the use of iron supplementation in pregnant women

In settings where anaemia in pregnant women is a severe public health problem (40% or higher), a daily dose of 60 mg of elemental iron is preferred over a lower dose.

If a woman is diagnosed with anaemia at any time during pregnancy, she should be given daily iron (120 mg of elemental iron) and folic acid (400 μg or 0.4 mg) until her haemoglobin concentration rises to normal. She can then switch to the standard antenatal dose to prevent recurrence of anaemia.

The implementation of intermittent supplementation among non-anaemic pregnant women may require a strong health system to facilitate confirmation of non-anaemic status prior to the start of supplementation and to monitor anaemia status throughout pregnancy.

In malaria-endemic areas, iron and folic acid supplementation programmes should be implemented in conjunction with measures to prevent, diagnose and treat malaria during pregnancy

An iron supplementation programme may form part of an integrated programme of antenatal and neonatal care that promotes adequate gestational weight gain, screening of all women for anaemia at antenatal and postpartum visits, use of complementary measures to control and prevent anaemia (e.g. hookworm control), and a referral system to manage cases of severe anaemia.

Rationale and evidence

Worldwide, approximately 1000 women die every day from complications related to pregnancy or childbirth (185). VAD also remains a public health problem among women, affecting an estimated 19 million pregnant women (184), with the highest burden found in the WHO regions of Africa and South-East Asia. During pregnancy, vitamin A is essential for the health of the mother as well as for the health and development of the fetus. This is because vitamin A is important for cell division, fetal organ and skeletal growth and maturation, maintenance of the immune system to strengthen defences against infections, and development of vision in the fetus as well as maintenance of maternal eye health and night vision. Thus, there is an increased need for vitamin A during pregnancy, although the additional amount required is small and the increased requirement is limited to the third trimester. The prevalence of night blindness (as a consequence of VAD) is more common in the third trimester of pregnancy, and populations with a prevalence ≥5% are considered to have a significant public health problem. It is currently estimated that 9.8 million pregnant women are affected by night blindness worldwide.

According to two Cochrane systematic reviews, assessing the effects and safety of vitamin A supplementation in pregnant women (186, 187), it reduced the risk of maternal night blindness (one trial) and there was no difference in total fetal loss, rates of stillbirth and neonatal deaths between women given vitamin A compared with controls.

After an analysis of currently available evidence, WHO published a guideline indicating that vitamin A supplementation is not recommended during pregnancy as part of routine antenatal care for the prevention of maternal and infant morbidity and mortality. The use of a supplement is only recommended for the prevention of night blindness when there is a severe public health problem related to vitamin A, as indicted in the recommendation quoted above.

Other interventions such as dietary diversification and food fortification can be used along with vitamin A supplementation to improve vitamin A intakes. Pregnant women should be encouraged to receive adequate nutrition, which is best achieved through consumption of a healthy balanced diet.

Rationale and evidence

Pre-eclampsia is a hypertensive disorder that develops in approximately 5% of all pregnancies, usually after about 20 weeks gestation (190). In pre-eclampsia there are often problems with the placenta, along with increased blood pressure, that can reduce blood flow and therefore oxygen and nutrient supply to the baby. These conditions may result in intra-uterine growth retardation and possibly early delivery. Especially in lower-income settings, hypertensive disorders are the leading cause of infant mortality (191). Pre-eclampsia may also cause serious outcomes for the mother, such as kidney and liver problems, even progressing to stroke or seizures (eclampsia) if not treated. Hypertensive disorders such as pre-eclampsia are thought to account for up to 40 000 maternal deaths per year.

Most women are monitored for increasing blood pressure during antenatal visits. Preventive measures may assist in the prevention of prenatal complications and adverse outcomes for women at increased risk of hypertensive disorders, such as those with multiple pregnancies, older age or increased BMI (192). Calcium supplements may reduce the chance of developing pre-eclampsia, especially in high-risk women, as well as those who do not consume sufficient quantities of calcium in their diet (193, 194, 195, 196, 197). Recent studies have supported this hypothesis, although there have been some inconsistencies in the strength and public health applications of the associations (198, 199). In addition, the possible biological actions of prenatal calcium supplementation are not completely understood.

Calcium is an essential mineral that assists with many of the body's processes, such as maintaining cell membranes in nerve as well as muscle contraction (200). Low calcium intake is thought to cause high blood pressure by increasing the amount of calcium released in the cells of blood vessels, possibly leading to the constriction of these tissues. By supplementing with calcium during pregnancy, the amount of cellular calcium released is lessened, as is smooth muscle tissue contractility. These mechanisms could prevent preterm labour and delivery by reducing uterine muscle contractions, and perhaps improving utero-placental blood flow (201).

During pregnancy and lactation calcium supplementation is often recommended to meet the body's demands to benefit the overall health of mother and child. Dietary reference intakes for pregnant women range from 1000 to 1300 mg per day, according to age group, with an upper limit set at 2500 mg/day (202). Although providing extra calcium supplements to prevent hypertensive disorders is relatively inexpensive and accessible, large doses of > 500 mg/day are less efficiently absorbed and may inhibit the absorption of other necessary micronutrients such as iron, zinc, magnesium and phosphorus (203, 204).

According to a recent Cochrane systematic review, supplementation with at least 1 g of calcium is associated with significantly lower risk of pregnant women developing pre-eclampsia and preterm birth among women with low calcium intakes. However, the public health implications for this intervention are not completely clear. Another recent study determined that calcium supplementation in pregnant women with low calcium intakes may not necessarily benefit maternal bone health (205). Conflicting evidence exists on the benefits of maternal calcium supplementation on the blood pressure of their offspring (206, 207, 208).

In summary, as indicated in the most recent WHO guidelines, there is clear evidence to show that daily supplementation with 1.5 to 2 g of elemental calcium is beneficial to reduce the risks of gestational hypertension, pre-eclampsia and preterm birth (189).

Rationale and evidence

Based on new evidence and lessons learned within the last decade, it appears that pregnant and lactating women might not be adequately covered by iodized salt where USI is not fully implemented. This situation may jeopardize the optimal brain development of the fetus and young child.

Irrespective of where countries, or areas within countries, are categorized with regard to USI, there are specific situations, such as in emergencies, among displaced people and geographically remote areas, where iodized salt may not be accessible. In these specific situations, increasing iodine intake should be provided in the form of iodine supplements for pregnant and lactating women, and a supplement or complementary food fortified with iodine for children 6–23 months of age.

In cases where it is difficult to reach pregnant women, supplementation to all women of reproductive age is advised.

Actions to promote optimal iodine nutrition in pregnant and lactating women

The actions summarized in the section on iodine in young children, pages 30–31, apply to pregnant and lactating women.

Rationale and evidence

During pregnancy and lactation, women's nutritional needs for energy, protein and micronutrients significantly increase. Pregnant women require an additional 285 kcals/day, and lactating women require an additional 500 kcals/day. Both pregnant and lactating women have increased needs for micronutrients. Adequate intake of iron, folate, vitamin A and iodine are particularly important for the health of both women and their infants.

Intra-household food distribution practices in many situations result in pregnant and lactating women consuming less than their minimum requirements. The consequences of poor nutritional status and inadequate nutritional intake for women during pregnancy and lactation not only directly affect the women's health status but may have a negative impact on infant birth weight and early development. Therefore, to meet the additional requirements of pregnancy and lactation, complementary interventions may be undertaken in addition to the provision of a basic food ration.

Appropriate complementary actions to meet the additional needs of pregnant and lactating women in emergencies (152)

Preventing and controlling micronutrient deficiencies: multiple vitamin and mineral supplements

The groups most vulnerable to micronutrient deficiencies are pregnant and lactating women and young children, mainly because they have a relatively greater need for vitamins and minerals and are more susceptible to the harmful consequences of deficiencies. For a pregnant woman these include a greater risk of dying during childbirth, or of giving birth to an underweight or mentally-impaired baby. For a lactating mother, her micronutrient status determines the health and development of her breastfed infant, especially during the first six months of life.

One way to meet the recommended daily intake of micronutrients is to provide foods fortified with micronutrients. Fortified foods, such as corn-soya blend, biscuits, vegetable oil enriched with vitamin A and iodized salt, are usually provided as part of food rations during emergencies. The aim is to avert micronutrient deficiencies or prevent them from getting worse among the affected population. Such foods must be appropriately fortified, taking into account the fact that other unfortified foods will meet a share of micronutrient needs. However, foods fortified with micronutrients may not meet fully the needs of certain nutritionally vulnerable subgroups such as pregnant and lactating women. For this reason UNICEF and the WHO have developed the daily multiple micronutrient formula shown in Table I-13 to meet the RNI of these vulnerable groups during emergencies.

Table I-13

Composition of multiple micronutrient supplements for pregnant and lactating women, designed to provide the daily recommended intake of each nutrient (one RNI).

Pregnant and lactating women should be given this supplement providing one RNI of micronutrients daily, whether they receive fortified rations or not. Iron and folic acid supplements, when already provided, should be continued.