Recommended Dietary Allowances

Recommended dietary allowances, i.e. the intake levels sufficient to meet the requirements of nearly all healthy pregnant and lactating women, or adequate intakes are listed in Table 2 [7]. Even in affluent populations, habitual intakes of some critical nutrients may be marginal or deficient (‘hidden hunger’) [11].

Table 2. Dietary reference intakes (DRIs) of selected nutrients in pregnancy and lactation: recommended dietary allowances (RDA) and adequate intakes (AI)
Nutrient Pregnancy Lactation
Vitamin A, μg/day 
Vitamin C, mg/day
Vitamin D, μg/day
Vitamin K, μg/day
Folate, μg/day
Vitamin B
12, μg/day
Calcium, mg/day
Iodine, μg/day
Iron, mg/dl
Magnesium, mg/day
Phosphorus, mg/day
Zinc, mg/day
Total water, liters/day
770 (10%)
85 (13%)
5 (0%)
90 (0%)
600 (50%)
2.6 (8%)
1,000 (0%)
220 (47%)
27 (50%)
350 (12%)
700 (0%)
11 (38%)
3.0 (11%)
1,300 (85%)
120 (60%)
5 (0%)
90 (0%)
500 (25%)
2.8 (17%)
1,000 (0%)
290 (93%)
9 (–50%)1
310 (0%)
700 (0%)
12 (33%)
3.8 (41%)
The additional intake (%) compared to non-pregnant and non-lactating women of the same age group is given in parentheses. Data from the Food and Nutrition Board, Institute of Medicine, National Academies, USA. 1 Depends on blood loss at delivery.
Folic Acid. An adequate and early supply of the B vitamin folic acid during the first 8 weeks of pregnancy has a strong protective effect against neural tube defects (NTD; spina bifida, anencephaly) [12]. Folate fortification programs of grain products have been introduced in about 40 countries worldwide and have been shown to markedly reduce NTD incidence. Women of childbearing age who may become pregnant and women during at least the first 2 months of pregnancy should aim to reach an added intake of 400 μg/day of folic acid from supplements, fortified foods, or the combination of both. To prevent the recurrence of NTD in a subsequent pregnancy, the folic acid supply should be maintained at 400 μg/day, or if previously discontinued 4 mg/day should be taken [7].
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Supplements of folic acid, iodine and iron should begin before pregnancy. Other critical micronutrients may be supplemented during pregnancy.
Vitamin A is required for normal embryonic development. In populations with a high prevalence of vitamin A deficiency, supplements are desirable, while in developed countries routine supplementation is not recommended. High doses (>3,000 μg/day preformed vitamin A) in early pregnancy may be teratogenic and should be avoided. But in populations with vitamin A deficiency even a single high dose supplement (60,000 μg) can be safely given to breastfeeding women in the first 2 months after delivery. It has been estimated that about a quarter of the vitamin A requirement may be covered by β-carotene which is not teratogenic.

Iodine is needed for the synthesis of thyroid hormones. The most extreme manifestation of iodine deficiency in pregnancy is cretinism, but more subtle alterations in growth and developmental impairment are often overlooked. Salt iodization has been implemented in many countries to prevent iodine deficiency, but iodine monitoring continues to indicate suboptimal supplies. A supplement containing 100 μg/day iodine is recommended in Europe before and during pregnancy, and during lactation.

Iron deficiency in pregnancy increases the risk of maternal morbidity and mortality, premature birth, low birthweight and stillbirth. Many women start pregnancy with low iron stores. Infants of iron-depleted mothers have lower iron reserves, may develop iron deficiency earlier, and may have delayed mental and psychomotor development. The increased iron requirement during pregnancy usually cannot be covered by diet alone. Low dose iron supplements (20–40 mg/day) should optimally start before pregnancy. Breast milk iron levels are low and not increased by iron supplements after delivery, which rather serve to replenish maternal stores.

Zinc deficiency is common in developing countries, especially with parasitic infections. Zinc deficiency may cause malformations, growth retardation, and increased infant mortality. Zinc supplements during pregnancy are vital in populations at risk.

Calcium. The calcium transfer from the mother to the fetus is facilitated by calcium-regulating hormones, while the calcium levels in maternal serum and bone are protected. Calcium loss from bone occurs in breastfeeding mothers, regardless of dietary intake, and is reversed after weaning. Dairy products are good calcium sources. Alternatively, calcium supplements may be taken during pregnancy and lactation.

Vitamin D is required for absorption and utilization of calcium. Low serum 25-OH vitamin D levels are common in temperate climates, especially in winter and spring, but occur also in geographic locations with more sunshine where conventions do not allow sun exposure. Low fetal vitamin D stores can have long-term consequences for bone mineral content. In countries without vitamin D fortification of dairy products, pregnant women should receive vitamin D supplements at least during the winter, e.g. 5 μg/day [13].

Vitamin B12. A low vitamin B12 status is prevalent not only in strict vegetarians, but also in lacto-ovo-vegetarians, and even in those with habitually low meat consumption. A low supply increases the risk of abortions, preeclampsia and preterm delivery.

Vitamin B6 and Riboflavin. The vitamin B6 and riboflavin status of pregnant and lactating mothers is also critically reduced in many poor areas of the world.

Fat-Soluble Vitamins and Docosahexaenoic Acid. The concentrations of B vitamins, fat-soluble vitamins (A, D, E, K), and the long-chain polyunsaturated fatty acid docosahexaenoic acid in breast milk are dependent on maternal stores [11]. Women should have a regular dietary supply of these nutrients already in pregnancy, which continues in lactation (e.g. at least 200 mg/day of docosahexaenoic acid) [14].

Screening of all pregnant women for the risk of micronutrient deficiencies and provision of individually tailored advice is time-consuming and costly, indicators of micronutrient status in pregnancy are not easy to interpret, and some interventions may come too late to affect outcome, e.g. folic acid supplementation should start before conception for optimal prevention of neural tube defects.

Information and Education at the population level may achieve some effects and should be implemented starting from school age, but food fortification programs are more effective in achieving enhanced nutrient supplies on a population level. Most women who plan to become pregnant or are pregnant will benefit from supplements containing multiple micronutrients at adequate dosages.