Nutrition and pregnancy refers to the nutrient intake and dietary planning that is undertaken before, during, and after pregnancy. Nutrition of the fetus begins at conception. For this reason, the nutrition of the mother is important from before conception (probably several months before) as well as throughout pregnancy and breastfeeding. An ever-increasing number of studies have shown that the nutrition of the mother will have an effect on the child, up to and including the risk for cancer, cardiovascular disease, hypertension, and diabetes throughout life.
An inadequate or excessive amount of some nutrients may cause malformations or medical problems in the fetus, and neurological disorders and handicaps are a risk that is run by mothers who are malnourished. An estimated 24% of babies worldwide are born with lower than optimal weights at birth due to lack of proper nutrition. Personal habits such as consumption of alcohol or large amounts of caffeine can negatively and irreversibly affect the development of the baby, which happens in the early stages of pregnancy.
Caffeine consumption during pregnancy is associated with an increased risk of pregnancy loss. The available research favors the notion that the benefits of fish consumption during pregnancy outweigh the risks; however, the type of fish is important. Folic acid, which is the synthetic form of the vitamin folate, is critical both in pre- and peri-conception.
Nutrition before pregnancy
As with most diets, there are chances of over-supplementing. However, as general advice, both state and medical recommendations are that mothers follow instructions listed on particular vitamin packaging as to the correct or recommended daily allowance (RDA). Daily prenatal use of iron substantially improves birth weight, potentially reducing the risk of low birth weight.
Folic acid supplementation is recommended before conception, to prevent the development of spina bifida and other neural tube defects. It should be taken as at least 0.4 mg/day throughout the first trimester of pregnancy, 0.6 mg/day throughout the pregnancy, and 0.5 mg/day while breastfeeding in addition to eating foods rich in folic acid such as green leafy vegetables. Iodine levels are frequently too low in pregnant women, and iodine is necessary for normal thyroid function and mental development of the fetus, even cretinism. Pregnant women should take prenatal vitamins containing iodine. Vitamin D levels vary with exposure to sunlight. While it was assumed that supplementation was necessary only in areas of high latitudes, recent studies of Vitamin D levels throughout the United States and many other countries have shown a large number of women with low levels. For this reason, there is a growing movement to recommend supplementation with 1000 IU of Vitamin D daily throughout pregnancy. A large number of pregnant women have been found to have low levels of vitamin B12, but supplementation has not yet been shown to improve pregnancy outcome or the health of the newborn. Long-chain polyunsaturated fatty acids, specifically docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are beneficial for fetal development. Several studies have shown a lower risk of preterm delivery and low birth weight in mothers with higher intakes. Iron is needed for the healthy growth of the fetus and placenta, especially during the second and third trimesters. It is recommended that the first and third trimesters retain concentrations greater than 11 grams/deciliter and that the second trimester has levels above 10.5 grams per deciliter. It is also essential before pregnancy for the production of hemoglobin. There is no evidence that a hemoglobin level of 7 grams/100 ml or higher is detrimental to pregnancy, but it must be acknowledged that maternal hemorrhage is a major source of maternal mortality worldwide, and a reserve capacity to carry oxygen is desirable. Iron supplementation reduces the risk of maternal anaemia and iron deficiency in pregnancy but the positive effect on other maternal and infant outcomes is less clear.
Nutrition during pregnancy The United States and the European Union have established vitamin and mineral recommendations during pregnancy and lactation. The amounts in the table below are the higher of the two. The citations separately list recommendations for pregnancy and lactation. Recommendations (RDAs = Recommended Dietary Allowances and PRIs = Population Reference Intakes) are set higher than what has been determined to be average requirements so as to address women who have above-average needs. For some nutrients, there is not enough information to set a recommendation, so the term Adequate Intake (AI) is used based on what appears to be sufficient.
Nutrient U.S. RDA or AI EU PRI or AIUnit Vitamin A 900 1300 μg Vitamin C 90 155 mg Vitamin D 15 15* μg Vitamin K 120* 70* μg α-tocopherol (Vit E) 15 11* mg Thiamin (Vit B1) 1.2 1.0 mg Riboflavin (Vit B2) 1.3 2.0 mg Niacin (Vit B3) 16 16 mg Pantothenic acid (Vit B5) 5* 7* mg Vitamin B6 1.3 1.8 mg Biotin (Vit B7) 30* 45* μg Folate (Vit B9) 400 600 μg Cyanocobalamin (Vit B12) 2.4 5.0* μg Choline 550* 520* mg Calcium 1000 1000 mg Chloride 2300* NE† mg Chromium 35* NE† μg Copper 900 1500* μg Fluoride 4* 2.9* mg Iodine 150 200* μg Iron 18 16 mg Magnesium 420 300* mg Manganese 2.3* 3.0* mg Molybdenum 45 65* μg Phosphorus 700 550* mg Potassium 4700* 4000* mg Selenium 55 85* μg Sodium 1500* NE† mg Zinc 11 14.9 mg
*Adequate Intake †Not established. The EU has not identified an AI for sodium or chloride, and does not consider chromium to be an essential mineral nutrient.
Vitamin and mineral supplements Multiple micronutrient supplements taken with iron and folic acid may improve birth outcomes for women in low-income countries. These supplements reduce the number of low birth weight babies, small for gestational age babies, and stillbirths in women who may not have many micronutrients in their usual diets. Undernourished women can benefit from having dietary education sessions and balanced energy and protein supplements. A review showed that dietary education increased the mother's protein intake and helped the baby grow more inside the womb. The balanced protein and energy supplement lowered the risk of stillbirth in small babies and increased weight gain for both the mother and baby. Although more research is needed into the longer-term effects on the mothers' and infants' health, the short-term effects look promising. A review conducted in 2018 found that there was a slight benefit for lipid-based nutritional supplements (LNS) for newborn birth weight, length, small for gestational age, and stunting when compared with iron-folic acid (IFA). In the same study, IFA and multiple micronutrients (MMN) reduced maternal anemia better than LNS, but care is advised in interpreting and applying the results due to review limitations.
Prenatal vitamins typically contain increased amounts of folic acid, iodine, iron, vitamin A, vitamin D, zinc, and calcium over the amounts found in standard multi-vitamins. Currently, there is insufficient evidence that zinc supplements during pregnancy result in improved neonatal or maternal outcomes. The World Health Organization does not routinely recommend zinc supplementation for all pregnant women.
Approximately of calcium is accumulated during pregnancy, almost all of it in the fetal skeleton (25 g). Calcium supplementation may result in little to no difference in preeclampsia. Low-quality evidence also suggests that calcium supplementation may reduce the risk of the mother having the baby before the 37th week of pregnancy (preterm birth).
A mother's nutritional intake during pregnancy is believed to influence and possibly offer protective effects against the development of allergic diseases and asthma in children. Maternal intake of vitamin D, vitamin E, and zinc has all been associated with a lower likelihood of wheezing in childhood, suggesting a protective effect. Additionally, maternal intake of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) has been associated with a reduced risk of the development of eczema in childhood and reduced likelihood for infants to exhibit sensitivity to foods in the first year of life.
Folic acid Folic acid, which is the synthetic form of the vitamin folate, is critical both in pre- and peri-conception. Deficiencies in folic acid may cause neural tube defects (NTDs). Women who had 0.4 mg of folic acid in their systems due to supplementing 3 months before childbirth significantly reduced the risk of NTDs. More than 80 countries use fortification of certain foods with folic acid as a measure to decrease the rate of NTDs.
Vitamins C and E The combination of vitamin E and vitamin C supplemented to pregnant women does not appear to be efficacious for reducing risk of stillbirth, neonatal death, preterm birth, preeclampsia or any other maternal or infant outcomes, either in healthy women or those considered at risk for pregnancy complications. Antioxidant vitamins as dietary supplements have been proposed as having benefits if consumed during pregnancy. For the combination of vitamin E with vitamin C supplemented to pregnant women, a Cochrane review of 21 clinical trials concluded that the data do not support vitamin E supplementation – majority of trials alpha-tocopherol at 400 IU/day plus vitamin C at 1000 mg/day – as being efficacious for reducing risk of stillbirth, neonatal death, preterm birth, preeclampsia or any other maternal or infant outcomes, either in healthy women or those considered at risk for pregnancy complications. The review identified only three small trials in which vitamin E was supplemented without co-supplementation with vitamin C. None of these trials reported any clinically meaningful information. A second Cochrane review of 29 trials, published same year, reported on the same combination trials but added analysis of trials with vitamin C alone. The conclusion was that the data do not support routine vitamin C supplementation alone or in combination with other supplements for the prevention of fetal or neonatal death, poor fetal growth, preterm birth, or preeclampsia.
Vitamin B12 For vitamin B12, the U.S. Recommended Dietary Allowance (RDA) for pregnancy is 2.6 μg/day, for lactation 2.8 μg/day. Determination of these values was based on an RDA of 2.4 μg/day for non-pregnant women, plus what will be transferred to the fetus during pregnancy and what will be delivered in breast milk. However, looking at the same scientific evidence, the European Food Safety Authority (EFSA) sets adequate intake (AI) at 4.5μg/day for pregnancy and 5.0 μg/day for lactation. Low maternal vitamin B12, defined as serum concentration less than 148 pmol/L, increases the risk of miscarriage, newborn low birth weight and preterm birth. During pregnancy the placenta concentrates B12, so that newborn infants have a higher serum concentration than their mothers. What the mother-to-be consumes during the pregnancy is more important than her liver tissue stores, as it is recently absorbed vitamin content that more effectively reaches the placenta. Women who consume a small percentage of their diet from animal-sourced foods or who by choice consume a vegetarian or vegan diet are at higher risk than those consuming higher amounts of animal-sourced foods of becoming vitamin depleted during pregnancy, which can lead to anemia, and also an increased risk that their breastfed infants become vitamin deficient.
Food safety Pregnant women are advised to pay attention to the foods they eat during pregnancy to reduce the risk of exposure to substances or bacteria that may be harmful to the developing fetus. This can include potentially harmful pathogens such as listeria, toxoplasmosis, and salmonella. Intake of large amounts of retinol has been linked to birth defects and abnormalities.
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