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Editors

KristiinaSaarinen
MarjoMetsäranta

The Premature Infant in Outpatient Care

Definitions

  • A prematurely born infant denotes an infant that is delivered before the week 37+0 of pregnancy. Most premature infants weigh less than 2 500 g. Premature infants may be small (small for gestational age = SGA; small for date), normal (appropriate for gestational age = AGA) or large (large for date), as all other neonates.
  • A very small premature infant weighs less than 1 500 g at birth, and an extremely low birth weight infant weighs less than 1 000 g.
  • The corrected age, i.e. the developmental age, is calculated, instead of the date of birth, from the expected date of delivery determined according to the ultrasonography in early pregnancy or according to the last menstruation. Preterm birth does not accelerate the growth or development of the child. The corrected age corresponds better than the calendar age (i.e. chronological age) to the child's true biological age that starts at conception. The growth and development of the premature infant should be assessed according to the corrected age as long as the difference is important in practice. If the child was born before the 28th week of pregnancy the correction is necessary at the age of one year, and possibly at the age of two years, but not any more at the age of three.
  • Examination: see Physical Examination of the Newborn.

Growth

  • The growth of premature infants is assessed according to the corrected age.
  • During the first year of life, growth charts specially developed for premature infants are used. These charts allow the monitoring of weight without relating it to the (at this age) unreliable height. Before the estimated time of birth, the growth of a premature infant is evaluated using charts that are based on the birth weight of infants.
  • Infants weighing more than 1 500 g at birth grow evenly after they have attained birth weight (in 10-14 days).
  • The growth is almost invariably retarded in very premature infants because of suboptimal conditions after birth. As soon as nutrition is adequate a catch-up growth starts both in these infants and in infants with intrauterine growth disturbance (small for date). Absence of the catch-up growth indicates continued problems with nutrition or body functions, or some underlying disease.

Nutrition Taurine Supplementation in Preterm or Low Birth Weight Infants, Formula Milk Versus Donor Breast Milk for Feeding Preterm or Low Birth Weight Infants, Non-Nutritive Sucking for Promoting Physiologic Stability and Nutrition in Preterm Infants, Multinutrient Fortification of Human Breast Milk for Preterm Infants Following Hospital Discharge

Energy, proteins, minerals

  • The growth rate of premature infants is faster that that of full-term infants, resembling foetal growth. Thus the weight-adjusted need for nutrients and energy is higher in premature infants during the first weeks and months of life compared with full-term infants. Catch-up growth also increases the need for nutrients and energy. On the other hand, the stores obtained from the mother are small. Because of respiratory problems the amount of fluids may have to be restricted even to less than half of the normal weight-adjusted amount.
  • Infants weighing more than 1800 g at birth grow well on a diet similar to that of full-term infants.
  • Nutrition of very low birthweight infants differs from the nutrition of infants born full-term.
    • During hospital stay and after discharge breast milk needs to be fortified with proteins and minerals, or special preterm formulas are used. These formulas contain more energy, protein and trace elements than regular formulas.
    • The fortification can be finished or a switch to a regular formula can be made in most cases around the expected date of delivery, if the child grows well.
    • If the growth is poor even if energy intake is normal (110-135 kcal/kg/24 h), there are usually no grounds to increase energy intake unless a fat malabsorption disorder has been detected. Poor growth is most probably caused by the deficiency of some other nutrient, most commonly protein.
  • The use of any special nutritional products and dietary plans are instructed at the hospital.

Iron

  • Premature infants need more iron than children born at term because their blood volume and iron stores are small and their relative growth is rapid. Most of iron is transferred from the mother to the foetus during the last few weeks of pregnancy. Iron deficiency has a harmful effect on the growth and development of the brain and predisposes the child to iron deficiency anaemia.
  • Additional iron is usually administered up to the age of 12 months. Written instructions are provided for the parents. Liquid iron preparations are also available. These may discolour the erupting primary teeth; the phenomenon is harmless. An attempt can be made to prevent it by giving the child e.g. puréed fruit or water to rinse the mouth after the administration of the iron solution.

Vitamins

  • The vitamin stores of premature infants are small, and a surplus of vitamins is required during the first weeks because of rapid growth. The need for vitamin D addition is, however, normal, i.e. 10 µg = 400 IU/day (see also Vitamins). Vitamin D supplementation using a pharmacy-sold preparation, preferably in the form of D3 (cholecalciferol), is recommended for the whole growth period. For children from 2 to 18 years of age, the dose is 7.5 µg/day.
  • Special vitamin preparations containing vitamins A, B12, E, and folic acid are available for premature infants in order to guarantee good haematopoiesis.
  • The need for multivitamin addition depends on the type of milk or milk formula. Staff at the hospital and at the child health clinic advises on the use of the vitamin supplements.

Additional foods

  • The child begins to receive other foodstuffs on an individual basis because the fat and protein contents of the breast milk varies from mother to mother, and the composition of the milk also changes by the time the child grows.
  • Infants born week 34 or later follow the same instructions as infants born full-term: exclusive breastfeeding until 4-6 months' calendar age and introduction of additional foods at the calendar age of about 4-6 months.
  • For infants born before week 34 it is recommended to introduce additional foods at the corrected age of 3 months, i.e. at the calendar age of 5-8 months, depending on the level of prematurity. The nutritive content of breast milk and infant formulas is better than that of additional foods (purées and gruels). Early introduction of additional foods may reduce the infant's milk intake, hence impairing nutrition.
  • A milk thickener may be used, as necessary.
  • For infants born before week 34 meat purées are started at the corrected age of 4 months, with 2 servings per day in order to ensure sufficient intake of iron, minerals and trace elements. Meat contains rich amounts of protein. Poultry, fish and eggs can also be served.
  • If the child has constipation, prune purée can be tried for treatment.
  • Cereals (oat, barley, wheat, rye) are started at the corrected age of 4 months. Porridges are favoured over gruels.
  • Dietary restrictions or delaying the introduction of foods is not recommended.

Vaccinations

  • The BCG vaccination is usually given to infants at risk after the weight of 2.5 kg has been reached.
  • The rest of the immunization schedule can be carried out according to the calendar age (and not according to the corrected age) even if the premature infant is still in hospital care. Only the vaccination series against rotavirus is not started when the premature infant is in hospital care. The vaccination series against rotavirus may be started after hospital discharge if the child's calendar age is under 15 weeks when the series is started. There should be a minimum of 4 week's interval between BCG and other vaccinations.
  • An influenza vaccination is recommended for all premature infants over 6 months of age. Influenza vaccination is also recommended for persons who are in close contact with the infant.

Diseases

  • During the first year of life, premature infants need more medical services than full-term infants. The smaller the child the more care is needed. The most common causes are respiratory infections, inguinal hernias and need for rehabilitation.
  • Fever in a premature infant with corrected age of less than 3 months is an indication to refer the child without delay to the emergency department of a hospital for assessment.

Bronchopulmonary dysplasia (BPD)

  • BPD is defined as a chronic pulmonary disorder caused by oxygen and ventilator therapy in very premature infants. Continuation of respiratory difficulties and need for respiratory support during the first weeks of life are typical features.
  • The diagnosis of BPD is established at the age of four weeks and its severity grade is determined at the age that corresponds to the 36th gestational week.
  • The clinical symptoms include prolonged need of oxygen, excess mucus, rales, dyspnoea, and obstructive wheezing. In addition to the clinical symptoms the diagnosis is based on typical abnormalities on a chest x-ray and a typical history.
  • The treatment of the most severely affected infants consists of inhaled bronchodilators during infections and during the phases of excessive mucus production. If diuretics have been used, the medications are aimed to be stopped before the infant is discharged home as well as the fluid restriction is cancelled. In the most severe form of BPD, need of supplemental oxygen is prolonged, and an oxygen concentrator is needed at home. Right heart overload may also be detected. In such a case, the child is followed up by a paediatric cardiologist who is responsible for possible cardiac medication.
  • Ensuring sufficient nutrition is very important. The treatment and follow up of BPD is organised in specialized care.
  • Common viral infections in infants with BPD may increase breathing difficulties and lead to hospital admission. Because of this, the families of these infants are recommended to avoid contacts that entail exposure to infections.
  • Children with severe BPD are provided prophylactic palivizumab injections during epidemic periods of respiratory syncytial (RS) virus to prevent respiratory infections caused by the RS virus.

Sensory defects

  • Premature infants are subject to therapies that involve the risk of a hearing defect (e.g. ototoxic antimicrobial drugs). Even if the hearing of infants at risk is examined before hospital discharge using otoacoustic emission or evoked response studies, it is important to monitor the hearing during childhood as some of the defects appear only later.
  • Retinopathy of prematurity (ROP) usually is a problem with the smallest premature infants with the risk being highest in those born before gestational week 27. In addition to prematurity itself, oxygen therapy predisposes to retinopathy. The eyes of all infants born before week 31 are examined for retinopathy. Vision-threatening changes are treated with laser or with intravitreal injections of anti-vascular endothelial growth factor (VEGF).
  • Strabismus, disorders of refraction and functional vision problems of cerebral origin are more common in premature children compared with full-term children. The risk is particularly increased in infants born before 27 weeks of gestation. These children are examined by an ophthalmologist at the age of 3-4 years. Infants born at week 27 or later are followed up in customary periodic examinations at the child health clinic. If the child is suspected to have problems with vision he/she is referrer to an ophthalmologist for evaluation.

Psychomotor development Early Developmental Intervention Programs for Preterm Infants

  • The neurological development is monitored according to the same principles as in children born at term. During the first 1-2 years of life, the corrected age is used for assessment of the developmental stage; in children born before week 30 it can be used up to the age of 18-24 months. In children born later using the correction can be discontinued earlier. Obvious developmental abnormalities require special investigations and assessment by a specialist.
  • However, the majority of infants weighing less than 1 500 g at birth develop normally although the risk of defects is increased.
  • Cerebral palsy, particularly hemiplegia, is a problem of very premature children. 5-10% of the very small premature infants develop motor disability and 25-50% have milder neurological, cognitive and behavioural problems that may lead to learning difficulties at school.
  • In children with a birth weight over 1 500 g or born after week 30 the prevalence of neurological problems is clearly lower. However, most cases of cerebral palsy are not associated with prematurity.
  • Examination of a newborn infant: see Physical Examination of the Newborn.

References

  • Sankilampi U, Hannila ML, Saari A et al. New population-based references for birth weight, length, and head circumference in singletons and twins from 23 to 43 gestation weeks. Ann Med 2013;45(5-6):446-54. [PubMed]

Evidence Summaries ⬆