Premature babies are newborns born at a gestational age of less than 37 weeks, and they can’t wait to come into the world, which not only brings surprise to young mothers and fathers, but also has many worries, especially how to feed these young babies is a big problem for parents. As we say, “food is the key to life”, and this is especially true for premature babies. Proper nutrition is not only related to the recent growth and disease regression, but also directly affects the long-term prognosis, so adequate and balanced nutrition is the material basis to ensure the healthy growth of preterm babies. What kind of milk is good for preterm babies? As premature babies are born early, their nutritional reserves are congenitally insufficient, and they need more nutrients for rapid growth after birth. On the other hand, their gastrointestinal tract is not yet developed and their digestion and absorption ability is poor, so babies born prematurely need special treatment. So what milk to eat to meet their needs? 1.Premature breastmilk: The caloric density of premature breastmilk is 67kcal/100 ml, but the composition is different from that of full-term breastmilk. Premature breast milk has a high protein content, which is beneficial to the needs of preterm babies for rapid growth; a high proportion of whey protein, which is good for digestion and accelerates gastric emptying; a low amount of fat and lactose, which is easy to absorb; a high sodium salt, which is good for replenishing the loss of preterm babies; calcium and phosphorus are easy to absorb, which is good for bone development. Compared to formula feeding, gastric emptying is faster after breastfeeding. Certain components in breast milk, including hormones, peptides, amino acids, and glycoproteins, play a role in the maturation of the small intestine. Lactoferrin, lysozyme, secretory IgA and interferon in preterm breast milk help protect preterm infants against infections including sepsis and meningitis and are very beneficial for this high-risk group of preterm infants. Breastfeeding reduces the incidence of necrotizing small intestinal colitis, which may be related to the protective effect of secretory IgA on the GI tract and the oligosaccharides in breast milk that prevent bacterial adhesion to the host GI mucosa. Premature breast milk is rich in long-chain polyunsaturated fatty acids (e.g. DHA) and taurine, 1.5 to 2 times more than mature breast milk, which promotes the development of the retina and central nervous system of preterm infants. Direct breastfeeding enhances emotional communication between mother and child, mother’s love and mother’s confidence. Current evidence suggests that the longer the duration of breastfeeding, the lower the chance of developing metabolic syndrome (obesity, hypertension, type II diabetes, cardiovascular disease) in the future. All of these aspects of benefit can positively influence the health and long-term prognosis of preterm infants. However, for preterm babies with low gestational age and low birth weight, the nutrients consumed by exclusive breastfeeding, including protein and minerals, are not enough for their growth, and their growth rate is slow, which may cause bone dysplasia and metabolic bone disease, so human milk fortifier (HMF) is often used abroad to ensure their nutritional needs for rapid growth. HMF contains protein, minerals and vitamins and is given to the baby in a certain ratio in breast milk (never directly in water or in formula). Breast milk fortification can be added during the hospitalization of preterm babies, once they have tolerated exclusive breastfeeding. Generally fortified breast milk prepared according to the standard can make its caloric density to 80~85 kcal/100 ml. There are several commercialized products of breast milk fortification in foreign countries, but it has not been introduced to China yet. 2. Premature formula: This is specially designed for premature babies and is used during hospitalization, with a caloric density of 80 kcal/100 ml. (2) Fat medium-chain fatty acids accounted for 40%, easy to digest and absorb. The high content of linoleic acid is conducive to promoting the growth and development of infant brain cells. (3) The carbohydrates include 40% lactose and 60% polydextrose, which supply the required calories without increasing the blood osmolarity. (4) Sodium content is increased to supplement the need for increased renal sodium excretion in preterm infants. (5) Calcium content is three times the normal breast milk content, making Ca:P close to ?2:1.(6) Vitamin and trace element fortification. In conclusion, preterm formula retains many advantages of breast milk, making protein, sugar, fat and other nutrients easy to digest and absorb, while appropriately increasing calories and fortifying a variety of vitamins and minerals to supplement the nutritional needs of breast milk for preterm infants. However, formula for preterm infants lacks many of the growth factors, enzymes and IgA found in breast milk. Generally speaking, the milk type suitable for preterm infants weighing <2000 g is fortified breast milk or preterm formula, and the former should be preferred both in terms of nutritional value and biological function. 3. Infant formula: i.e. formula for normal full-term infants with a caloric density of 67kcal/100 ml. Healthy preterm infants with gestational age, birth weight >2000 g, no serious complications and no risk factors for malnutrition can use infant formula directly. 4. Post-discharge formula for preterm infants: specially designed for preterm infants in the post-discharge transition period, its energy and nutrients provided between preterm formula and infant formula, with a caloric density of 73kcal/100 ml. After more than a decade of application, it has been proved that preterm babies who use this special formula after discharge from hospital achieve faster catch-up growth and stronger bone development than those who use regular infant formula. How do I breastfeed my preterm baby? At birth, many preterm babies, especially those born at less than 34 weeks of gestational age, are often unable to feed themselves due to immaturity and illness. The amount of milk may be very small at first, and will be increased gradually as the baby tolerates it more often each day. If the amount of milk is not enough, the doctor will give parenteral nutrition, which means that nutrients will be given through intravenous infusion, and when the baby has more milk, parenteral nutrition will not be needed. For preterm babies who are older, their sucking, swallowing and breathing are coordinated and they can feed themselves. However, due to the small capacity of the stomach, it is not possible to feed as much as a full-term baby at each feeding. It is normal for them to stop eating and rest for a while before eating again. Some babies are impatient and eat milk quickly, often holding their breath. This is the time to let him or her rest for a while and take a few breaths before continuing to eat. You must be very careful and patient when feeding your premature baby, picking him/her up and feeding him/her to avoid choking and spitting up as much as possible. If breastfeeding, the mother’s milk will often choke if there is a lot of milk and the flow is fast, because the baby will not have time to swallow. In this case, the mother can pinch her fingers around the areola to slow down the flow of milk, or squeeze out some of the milk in front of her before letting her baby eat. Since the composition of the front milk and the back milk of breast milk is different, the front milk has more protein and the back milk has more fat, which are indispensable for premature babies, so it is important to eat the empty side before eating the other side. When feeding manually, choose the right pacifier, too big will choke, too small and laborious. Do not leave it at room temperature for too long. Pay attention to the cleanliness of the breastfeeding utensils and disinfect them daily. After each feeding, pick your baby up vertically and pat his or her back on the mother’s chest. This is to help the baby expel the gas that was taken in at the same time while breastfeeding to avoid spitting up. Before the age of 3 months, many babies will spill milk, that is, some milk will flow out along the side of the mouth after eating milk, especially after the baby strains or moves. This is normal and will get better as they get older. If choking occurs, immediately turn your baby on its side or face down and pat its back to drain the milk from the nasopharynx to prevent choking. Which preterm babies need intensive feeding after discharge from the hospital? The current discharge criteria for preterm babies are a weight of about 2,000 grams and continued growth, complete oral feeding, and stable body temperature and vital signs at room temperature. However, at this time most preterm infants of small for gestational age have not yet reached their due date (40 weeks of gestational age), and some preterm infants with many complications have growth retardation. This suboptimal growth status will affect long term health and increase the risk of developing chronic diseases in adulthood. Previous nutritional support strategies have focused on the nutrition of preterm infants during their hospitalization and their transition to unfortified breast milk or full-term formula feeding when they reach discharge criteria. However, such nutritional regimens cannot fill the cumulative deficits in energy and protein in the early postnatal period and cannot meet the catch-up growth requirements of preterm infants. In recent years, authoritative academic institutions both at home and abroad have emphasized the importance of continued nutritional fortification of preterm infants after discharge from the hospital, with the aim of helping preterm babies achieve an ideal nutritional status to meet their needs for both normal and catch-up growth. The normal growth trajectory of infants is influenced by genetics and gender, while catch-up growth depends on a variety of factors such as gestational age, birth weight, degree of illness, nutrition during hospitalization and growth status before discharge, and varies greatly between individuals, so the post-discharge nutritional management strategy is individualized and under the guidance of experienced physicians. According to the recommendations for feeding preterm infants in China, the targets of post-discharge intensive nutrition are preterm infants with the following high-risk factors for malnutrition: 1. very low birth weight infants (birth weight <1500 g) and ultra-low birth weight infants (birth weight <1000 g); 2. in- and out-of-utero growth retardation; 3. critical conditions and complications after birth; 4. birth weight <2000 g and purely breastfeeding during hospitalization; 5. Breastfeeding; 5. Complete parenteral nutrition >4 weeks; 6. Unsatisfactory weight gain [<15g/(kg?d)] before discharge. How to choose the feeding method after discharge? Experienced doctors should be consulted before discharge of preterm babies to choose a reasonable feeding method. 1.Breast milk: For preterm babies with birth weight >2000g and no risk factors for malnutrition, breast milk is still the first choice after discharge. Pay attention to the mother’s diet and balanced nutrition. 2.Breast milk + breast milk fortification: Very (ultra) low birth weight infants and those with unsatisfactory nutritional status evaluated before discharge need to continue breast milk fortification until 40 weeks of gestational age. Thereafter the caloric density of breast milk fortification should be slightly lower than during hospitalization, such as half amount of fortification (73 kcal/100 ml), depending on the growth. Since breastfeeding is especially important for preterm babies, the mother should insist on expressing milk to the hospital every day during the baby’s hospitalization. You can freeze the breast milk if you can’t finish it, and there is no problem in 6 months. This way the mother’s milk will get more and more and when the baby is discharged from the hospital she can continue to get breast milk. 3. Premature formula: artificially fed very (ultra) low birth weight babies need to be fed until 40 weeks of gestational age; if breastfeeding weight gain is not satisfactory it can be mixed (preterm formula not more than 1/2 of the total daily amount) as a supplement to breast milk. 4. Post-discharge formula for preterm infants: applicable to artificially fed preterm infants or as a supplement to breast milk. 5. Infant formula: Applicable to preterm babies with birth weight > 2000 grams, no risk factors for malnutrition, satisfactory weight gain after discharge from hospital and artificially fed or as a supplement to breast milk when breast milk is insufficient. How long does it take for preterm babies to be discharged from the hospital for intensive feeding? Post-discharge intensive nutrition for preterm babies is a method of feeding with fortified breast milk, preterm formula and post-discharge formula for preterm babies. Fortified nutrition can ensure good growth and neurological prognosis of preterm infants, but overfeeding can cause obesity and metabolic syndrome in the future, so how to strike a balance between the two is a problem that needs to be solved. The timing of intensive nutrition has not been standardized across countries and is still controversial. According to the current principles of evidence-based medicine, it is recommended to be applied until the corrected age of 3 months to 6 months. However, it must be judged under the guidance of a physician based on the nutritional status and its physical developmental monitoring indicators including growth curves of weight, length, head circumference and whether the nutritional and biochemical indicators are normal in preterm infants during regular follow-up after discharge from the hospital, with full consideration of individual differences. When switching babies to formula, such as from preterm formula to post-discharge formula for preterm infants, or from post-discharge formula to infant formula, a gradual approach should be taken. For example, if you feed 8 times a day, add 1 time of the new formula first and the remaining 7 times of the old formula. Observe for 2-3 days to get used to it and then increase to 2 times the new formula and the remaining 6 times the old formula… until you have completely changed to the new formula. During the conversion process, many babies may not be used to the taste or intolerance, but they will always get used to it slowly, so don’t rush. How to add complementary foods for preterm babies? There are individual differences in the age at which preterm babies can be introduced to complementary foods, which is related to their maturity level. Premature infants with small gestational age are introduced relatively late, generally not earlier than 4 months of corrected age and not later than 6 months of corrected age. The order of introduction is also between the corrected and actual ages. Adding complementary foods too early can affect milk quantity or lead to indigestion, while adding them too late can affect the absorption of many nutrients and cause feeding difficulties. The principle of adding complementary foods is gradual, from one to many, from less to more, from thin to thick. Premature babies need to learn to eat, such as chewing, swallowing function exercise, oral muscle movement coordination, etc.. However, within 1 year old, milk is the main food for babies, the amount of supplementary food should not be too much, but there should be more patterns, so that they can get sufficient and balanced nutrients and develop good habits of not being picky eaters. How to supplement vitamin D and iron for premature babies? The role of vitamin D is to promote the absorption of calcium and phosphorus and their deposition in the bones. Premature babies have insufficient calcium and phosphorus reserves, and their needs for vitamin D and calcium and phosphorus are much higher than those of full-term babies in order to meet the rapid growth after birth. According to our “Recommendations for the Prevention and Treatment of Vitamin D Deficiency Rickets”, premature babies should receive vitamin D supplementation of 800?1000 U/d immediately after birth, changing to 400 U/d after 3 months until 2 years of age. This supplementation includes vitamin D content in food, sun exposure, and vitamin D preparations. Premature babies have low iron reserves and are very prone to anemia, which directly affects physical and neurological development. According to the recommendations of domestic and foreign experts, preterm babies need to start elemental iron supplementation 2?4 mg/(kg?d) 2 weeks after birth until the corrected age of 1 year. This supplementation includes the iron content of iron-fortified formula, breast milk fortification, food and iron preparations. Do preterm babies need supplements? We say that the most important nutrient your preterm baby needs is milk, including the breast milk and the special formula for preterm babies mentioned above. Some babies may have a zinc deficiency, which can be supplemented if they have growth retardation, loss of appetite, and low blood trace elements of zinc. Other than that, it is not necessary. How to assess the nutritional status of preterm babies? The evaluation of the nutritional status of preterm babies is a complex process, which includes measuring their longitudinal growth rate and comparing them with the same age group, including growth and development and monitoring their skeletal and nutritional biochemical indicators. 1, growth evaluation indicators: basic indicators include weight, length and head circumference. Since there is no growth standard for preterm infants in China, the actual growth level of preterm infants should be determined by comparing their monthly (annual) age after correction (calculated from full term, i.e. 40 weeks of gestational age) with the growth standard of full-term infants within 2 years of age. It is recommended that the 2005 Chinese Child Growth Standards for nine provinces and cities be selected and the percentile method be used. The growth of preterm infants during hospitalization was referred to the growth rate of normal fetuses in utero, with an average weight gain of 15 g/(kg?d), length growth of 1 cm/week, and head circumference growth of 0.5 to 1 cm/week. After discharge from the hospital, since the catch-up growth of preterm infants often manifests itself within 1 year of age, especially in the first 6 months, the ideal level of weight gain within 6 months of corrected age should be above the 25th?50th percentile of the standard for the same age, followed closely by length growth, while head circumference growth is particularly important for neurological development. Premature babies should be weighed daily during hospitalization, and their length and head circumference should be measured weekly. After discharge from the hospital, it should be measured once a month within 6 months of age, once every 2 months from 6 to 12 months of age, and once every 3 months from 1 to 2 years of age. 2. Biochemical evaluation indicators: Commonly used nutritional indicators include non-protein nitrogen, alkaline phosphatase, calcium, phosphorus and prealbumin. Premature infants will be retested every 2 weeks during hospitalization and 1 month after discharge if the biochemistry is abnormal at the time of discharge. Retesting for evaluation is required when growth retardation occurs or when ready to switch to exclusive breast milk or standard formula feeding. In conclusion, the goals of nutritional management for preterm infants should meet the following objectives: 1) to meet the needs of growth and development; 2) to promote the maturation of various tissues and organs; 3) to prevent nutritional deficiencies and excesses; 4) to ensure the development of the nervous system; and 5) to facilitate long-term health.