In February 2019 researchers from Germany, UK, Poland, The Netherlands and Australia who were part of the The Early Nutrition Project published their review of the medical scientific literature and existing recommendations to form updated, generally agreed, recommendations on nutrition and lifestyle before and during pregnancy, and during infancy and early childhood. Most current recommendations for pregnant women, particularly obese women, and for young children do not take long-term health consequences of early nutrition into consideration, although the available evidence for relevant consequences of lifestyle, diet and growth patterns in early life on later health and disease risk is strong.
The researchers were in general agreement with the following recommendations:
Nutrition Pre-Pregnancy
Many women and adolescent girls are poorly nourished due to an inadequate or an imbalance in their diets, leading to underweight, overweight/obesity and nutrient deficiencies. However, very few attempts are made to change their lifestyle in preparation for pregnancy, even though most pregnancies are thought to be generally planned. Therefore many women have an unhealthy lifestyle as they start their pregnancy, eg poor quality diet, low levels of physical activity, smoking and excessive alcohol consumption, which has a major influence on both pregnancy outcomes and the child’s risk of becoming obese and contracting non-communicable diseases. It is therefore recommended that women of reproductive age should pay particular attention to their body weight and BMI, and where appropriate seek advice to achieve a healthy weight by improving diet, lifestyle and physical activity prior to falling pregnant.
Undernutrition is also important as underweight women are more likely to be deficient in important nutrients, and their diet should be carefully assessed and supplemented as required. Dietary supplementation with iron, vitamin D, vitamin B12, iodine, and other nutrients may also be required in women at risk of insufficiency. Particular attention should be paid to the intake and status of some micronutrients, especially folate, in women of reproductive age. Plant-based foods including green leafy vegetables, cabbage, legumes, whole grain products, tomatoes and oranges are good dietary folate sources, but additional supplementation of folic acid may be required. This has been shown to markedly reduce the risk for serious birth defects, eg neural tube defects, and some studies have shown a reduced risk for other congenital birth defects, like congenital heart disease and cleft palate. Folate-enriched foods should be promoted as an effective strategy to reduce the risk of congenital malformations.
Nutrition during Pregnancy
Pregnant women should consume a balanced diet in accordance with dietary recommendations for the general population. The idea that the mother should “eat for 2” is a myth. International recommendations suggest that during pregnancy, women increase their energy intake by about 85 kcal per day in the first trimester, 285 kcal per day in the second trimester and 475 kcal per day in the third trimester. However, as the level of physical activity tends to be lower, particularly in the third trimester, dietary intake generally does not need to increase by more than about 10% at the end of pregnancy. It should be noted that factors which may indicate a greater energy requirement include adolescent pregnancy, hard physical labour/high physical activity, being pregnant with more than one offspring, and infections or malabsorption disorders. Maternal obesity, excessive weight gain, as well as diet during pregnancy has been associated with the child being overweight or obese as well as cardiovascular risk factors.
There was general agreement that pregnant women should aim to consume 2 portions of fish each week, including one portion of oily fish such as mackerel, herring, sardines or salmon. However consumption of the larger predator types of fish, eg tuna, swordfish, should be avoided as these may contain high amounts of toxic substances such as methylmercury and lipid soluble pollutants. The researchers recommended that those women who do not consume fish on a regular basis should consider taking a supplement of at least 200 mg omega-3 polyunsaturated acid per day. Regular consumption of fish as well as supplementation of omega-3 polyunsaturated fatty acids was found to reduce the risk of early preterm birth prior to 34 weeks of gestation. It also appears to reduce the risk of low birthweight and also, possibly, of pre-eclampsia. However, it should be noted that a very high fish intake of more than 3 portions per week during pregnancy has been associated with higher BMI in early childhood. Girls appear to be more affected by this than boys.
The researchers endorsed previous recommendations on folic acid supplementation before conception and in early pregnancy as dietary intake is usually inadequate, and adequate folate status contributes to the prevention of congenital birth defects. Folate supplements should be continued during at least the first 16 weeks of pregnancy. In addition dietary supplementation with iron, vitamin D, vitamin B12, iodine and vitamin A may also be required in women who are at risk of an insufficiency in these micronutrients. Women who follow a vegan or vegetarian diet may have low levels of vitamin B12 and vitamin B12 supplementation should be considered here. It should be noted that the B vitamins are necessary for optimal health in pregnancy and for foetal growth and brain development. Vitamin D is required for foetal bone development and spending time outdoors can help to provide a sufficient supply of vitamin D, although sunburn should of course be avoided. Women who live in environments with insufficient sun exposure, who are dark skinned and live in areas of low sun exposure, or whose clothing or use of sunscreen prevents sufficient exposure, are at risk of vitamin D insufficiency. Maternal deficiency if vitamin D can result in childhood rickets and osteopenia in the newborn and has also been linked to low birth weight, increased risk of neonatal hypocalcaemia, cardiac failure and reduced bone density in childhood.
The requirement for many nutrients increases significantly only after the first trimester of pregnancy, whereas an increased intake from conception or even before conception is recommended for folic acid, iodine and iron. However, pregnant women should avoid taking nutritional supplementation at doses markedly exceeding daily reference intakes. A very high intake of micronutrients, markedly exceeding requirements, does not have any benefit. In fact, it might induce adverse side effects and therefore this is not recommended. Particular concern exists regarding excessive intakes of vitamin A (retinol) in pregnant women with no evidence of vitamin A insufficiency, which has been associated with liver dysfunction and birth defects. There is also a potential risk that larger doses of vitamins C and E may increase the risk of small for gestational age babies. In fact there is no evidence in the medical literature that combined vitamin C and E supplementation during pregnancy prevents foetal or neonatal death, poor foetal growth, preterm birth or pre-eclampsia.
It was generally agreed that raw animal-based foods, including raw or not thoroughly cooked meat, salami and other raw sausages, raw ham, raw fish, raw seafood, unpasteurized milk, raw eggs, as well as foods made of these products, which are not thoroughly cooked should be avoided during pregnancy.
Raw fruit and vegetables as well as lettuce should be washed well before consumption, be prepared freshly, and be eaten soon after preparation. In fact some researchers state that pregnant women should avoid eating pre-prepared, packaged salads.
Foods that are grown in or near to the ground should be stored separately from other foods to avoid cross-contamination. In addition, it is also felt that such foods should be always be peeled.
Food-borne illnesses such as listeria and toxoplasmosis can cause severe foetal damage, premature birth and stillbirth. Toxoplasmosis may be transmitted via raw or not fully cooked meats and meat products from pork, lamb and game, and with a lesser risk from beef. Raw meat products, smoked fish and soft cheeses, unpasteurized milk and products containing unpasteurized milk products, and vegetables and salads may transfer listeria which can multiply at cool temperatures in a refrigerator, and also in vacuum-sealed packed foods and pre-packed salads. Raw, animal-based foods may also transmit other infections, with particularly high risks in pregnancy, such as salmonella.
Recommendations on Nutrition of Breastfeeding Women
It was generally agreed that breastfeeding women should consume a balanced diet which provides an adequate nutrient intake and at the same time promotes a reduction of post-partum weight retention. In addition, breastfeeding women should not be encouraged to modify or supplement their diet as this can increase the infant’s risk of becoming overweight or obese later in life. It has been seen, for example, that vitamin D and live bacteria in the form of probotics has no affect on the infant’s later risk of becoming overweight or obese.
Recommendations on Nutrition in Infants and Young Children
Feeding practices in infants and young children should aim to achieve a weight gain similar to the normal weight gain which has been defined by generally accepted growth standards. Rapid weight gain in infancy and in the second year of life over and above this has been consistently associated with an increased subsequent obesity risk. Higher total energy consumption, poor diet quality and dietary energy density in early childhood have all been linked to a later increase in BMI and the child becoming overweight or obese. Both under- and overfeeding should be avoided, and energy and nutrient intakes should be adapted to achieve a weight gain similar to the normal weight gain defined by generally accepted growth standards.
There was general agreement that breastfeeding, if at all possible, should be promoted and supported, and that partial breastfeeding is better than none at all. This is because breastfeeding is associated with numerous benefits. Compared with breastfeeding, feeding conventional infant formula induces a higher average weight gain during the first year of life and beyond. It is only in rare cases that exclusive breastfeeding may also induce excessive weight gain, eg when there is a higher maternally produced protein content in the breast milk than normally expected. Overall, breastfeeding for a period of six months is associated with a 12-14% reduction in risk for the child becoming overweight or obese in childhood and adult life, whereas a very short duration of breastfeeding appears to decrease this risk reduction.
Infants born at term who are not breastfed should receive an infant (or from 6 months on a follow-on) formula with a protein supply approaching that provided with breastfeeding. Lowering the protein content of formula provided to infants appears to be a promising intervention that can reduce the risk of the child becoming overweight or obese. Formula with reduced protein content has been seen to prevent excessive early weight gain and a markedly reduced incidence of obesity at early school age. The provision of protein-reduced infant formula for infants of mothers who were overweight or obese has in fact been reported to provide considerable long-term health benefits.
No beneficial effects with respect to later obesity risk has been seen in connection with the use of formula soya milk or with added non-digestible carbohydrates (or “prebiotics”), live bacteria (or “probiotics”) or long-chain polyunsaturted fatty acids.
It was generally agreed that regular cows’ milk or other regular animal milks (other than specially designed and targeted to children using animal milk as a nutrient source) should be avoided as a drink in the first year of life, and to limit consumption of those dairy milks to about 2 cups per day in the second year of life, whenever feasible. Regular cows’ milk and milk of many other animals, such as goat or buffalo milk, contain about 3–4 times more protein per unit energy content than human milk or modern infant formula and carries with it the risk of inducing very high protein intakes. High intakes of protein and particularly of dairy protein during infancy and early childhood, in the order of 10–15% of energy intake or more, have been consistently associated with increased weight gain and a higher risk of becoming overweight or obese.
There was general agreement that complementary foods should not be introduced before the infant reaches the age of 17 weeks and not later than 26 weeks. However, the World Health Organisation recommends exclusive breastfeeding to 6 months, with complementary foods only being introduced at this age. This is seen to be an intervention to reduce morbidity and mortality from gastrointestinal and respiratory infections particularly in low- and low-medium-income countries. Some studies have shown that the introduction of complementary food before 15 weeks of age may increase the risk of the child becoming overweight whereas variation in the introduction of complementary feeds between 17 and 26 weeks of age does not appear to be associated with consistent differences in growth or an alteration of obesity risk. An association between a higher dietary protein intake in early childhood and the child becoming overweight or obese has been reported, although no conclusive evidence has been seen of an association between the intake of fat, dairy products, calcium, fruits and vegetables in early childhood and later BMI or adiposity.
Dietary sugar intake with beverages and foods in infancy and early childhood should also be avoided as there is some evidence that suggests an association between sugar-sweetened beverage intake in early childhood and the later risk of overweight and obesity.
Koletzko B et al. Nutrition During Pregnancy, Lactation and Early Childhood and its Implications for Maternal and Long-Term Child Health: The Early Nutrition Project Recommendations. Ann Nutr Metab. 2019;74(2):93-106.