HUNGRY FOR MORE
Proper postnatal nutrition is needed to help make up for intrauterine malnutrition
By Michelle Ciriacruz
In the womb, the infant is awash in a sea of nutrients that allows it to reach optimal growth and development. The influx of nutrients comes from the mother: the placenta is the interface; and the circulatory system the baby's supply route.
However, says perinatologist Corazon Yabes-Almirante, certain cases, like inadequate nutrition of the mother or a mother with preeclampsia, could cause a problem in this utero-placental circulation-preventing the infant from growing to its maximum weight for lack of adequate sustenance.
If the baby reaches full term in the womb, it is born low in weight, in appearance as mature as normal babies but with a weight that falls below the standard for its gestational age.
And if the baby is born premature, it is born deprived not only of a longer gestation but also of some of the enzymes important for brain and tissue development. In the last trimester, for example, the placenta extracts special fatty acids, like arachidonic and docosahexaenoic acids, from maternal circulation to pass on to the infant. Without these chemicals, neural and endothelial cells will not grow, and if supply is meager, will not function properly.
A low-birth-weight (LBW) baby is thus born with nutritional deficits that hamper its growth and development. Studies have shown that there is a close association between neurodevelopmental disorders and low birth weight. In a paper1 published by Dr. Michael Crawford of the Institute of Brain Chemistry and Human Nutrition at the Queen Elizabeth Hospital for Children, London, he cites evidence of this.
He reports that in a survey of congenital malformations in infants born in England and Wales from 1981 to 1985 (Office of Population Censuses and Surveys), it was found that the risk rises sharply from 6/1,000 to over 200/1,000 live births among those born below 1,500 grams.
And as shown by a good number of studies published in different scientific journals, the incidence of neuromotor impairment and neurobehavioral dysfunctions among LBW infants is significantly high.
Crawford emphasizes: "The risk of these neurodevelopmental disorders increases sharply as birth weight falls."
Hunger in the Womb, Hungry When Born
This intrauterine malnutrition is particularly hard on the premature infant, abruptly denied placental enrichment and confronted with a near-starvation situation.
According to University of Iowa pediatrician Ekhard Ziegler (in a paper presented at the 5th International Workshop on maternal and extrauterine nutritional factors: their influence on fetal and infant growth), nutritional support is crucial.
The goal is "to restore the influx of nutrients immediately to a level that permits continuation of growth and development."
The goals of nutritional support for an LBW term infant are also as compelling. The fact that it has not gained the proper weight tells that something is wrong somewhere, Almirante points out.
Pediatrician Lourdes Ann Dizon-Co explains that "while hospitalized, these infants don't only require ongoing basic nutritional needs, which may be increased above those of more mature, larger babies, but actually have deficits due to unmet nutrient delivery in utero-perhaps related to maternal/placental conditions or simply due to a prematurely interrupted gestation."
Their nutritional regimen, therefore, should meet any or all of these goals: defining and achieving a standard of short-term growth, preventing feeding-related morbidities, and optimizing long-term outcome, cites Co.
She says that identifying the ideal goal depends on which of these end points is desired-an end point that would be made more difficult to reach by a variety of gastrointestinal problems, however.
"The intestinal tract of preterm neonates, almost all of whom are LBW, has not reached full functional capacity and is vulnerable to the development of necrotizing enterocolitis and enteric pathogens, as well as delayed growth and development," she explains.
These LBW infants may have uncoordinated suck, swallow, and breathing reflexes and can tolerate a limited volume of feedings. "Feeding intolerance can present as abdominal distension, vomiting, tenderness, gastric residues, and colic," she describes.
But recent technical innovations have done much to overcome these difficulties. For the very difficult cases, the development of materials and techniques for the percutaneous insertion of central vein catheters has made it possible to go ahead with aggressive nutrition via the parenteral route.
"Most of the time, gavage or tube feed, which is more time consuming for the nurse, is the method of choice for feeding LBW and premature babies. Their gestational age, neurological impairment, respiratory rate, and stamina are always taken into consideration, [however]," Co stresses.
Traditionally, the goal of nutritional support for LBW infant was only to maintain its homeostasis. This provided water, electrolytes, and some energy in the form of glucose. Studies have shown, however, that keeping to this method will not improve survival rates and prevention of neurological disorders among LBW infants.
Relates Co: "Recent emphasis has been given to 'early, aggressive nutrition' in the extremely-low-birth-weight (ELBW, <1 kg) and very-low-birth-weight (VLBW, <1.5 kg) neonate beginning soon after birth."
Crawford's paper also details the findings that prompt feeding of LBW babies was advisable. "On recognition, they should be fed early, the incidence of cerebral palsy amongst low birth weight babies declined," he reports.
Co explains that "nutritional rehabilitation of LBW infants should begin as soon as possible to approximate continued growth at intrauterine rates." And that in all infants, "there is a brief period of physiologic weight loss postnatally." This could worsen with illness and caloric deprivation, she points out.
She continues: "When this period of postnatal weight loss ends, catch up growth should occur. During catch up growth, rates of gain for corrected age exceed intrauterine and postterm velocities of full-term infants."
Catch Up, Make Up
For LBW infants, premature or term, the burden of growth and development is greater with the need to catch up and to make up for lost nutrients while in the womb.
Ideally, the nutrition of a preterm LBW infant should be modeled on the placental provision. Technology is advancing towards that end, but meanwhile, human milk, especially colostrum, is the closest approximation we have that could supply the greater demand for calories, protein, minerals, and vitamins in an LBW infant.
But neonatologist Maria Andrea Alano says this is only partially true. Her paper, presented in the first Philippine Pediatric Society-NestleŽ Nutrition Intersubspecialty Conference, discussed why. "After 10 days of age, the preterm breast milk has the same protein content as term breast milk and will no longer satisfy the requirement of rapidly growing preterm infant."
Alano points out that "this special group of infants (VLBW and ELBW) needs higher protein intake because intrinsically they have higher rates of protein synthesis and turnover rates during the rapid growth phase and greater body proportion of rapidly growing organs earlier in gestation."
At best, human milk is a reference for small preterm infants, she says. A technique that could meet an LBW infant's greater need is human milk fortification. "Studies have shown that supplementation with human milk fortifier improved growth, protein status, and bone mineralization in premature infants," relates Alano.
Locally, human milk fortification is not practiced yet. As far as experience is concerned, Co says breast milk alone, breast milk fortified with a commercial breast milk fortifier, or special premature formulas go a long way toward providing the fundamental nutritional needs for these at-risk infants.
Gut Priming
Ziegler says that while the parenteral route is the easiest method for complete-or the closest we could come to it-nutritional support, trophic feeding should not be neglected. "It is important to prevent atrophy of the gastrointestinal tract, " he stresses.
This feeding method is strictly aimed at the gut, not at the baby, he explains. He cites studies that demonstrated a decrease in intestinal tissue in the absence of enteral feeding in the first few days of life.
"The feeding of choice is expressed breast milk (colostrum)," he says.
If the mother is unable to express milk, Co says that breast milk may be obtained from donors-mothers who are breastfeeding their own babies but have excess milk and are prepared to help other babies.
Potential breast milk donors are, of course, screened for illness and illegal drug use. They must also be nonsmokers and are not in a high risk group for exposure to HIV, hepatitis B and C, and other sexually transmitted disease.
Co says the following conditions interfere with normal gastrointestinal function of the LBW infant:
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Immature motility pattern
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Poor coordination of sucking and swallowing
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Incompetent lower esophageal sphincter
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Delayed gastric emptying time
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Poorly coordinated gastrointestinal motility
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Alltered digestion
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Decreased gastric acidity
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Decreased pepsinogen
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Decreased absorption of fat
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Incomplete digestion of protein
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Decreased activity of lactase
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Decreased secretion of immunoglobulins and impaired immunologic response
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Decreased rate of cellular proliferation and migration
Co explains that, to breastfeed, the premature LBW baby should be stable. They should meet the following criteria:
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Corrected gestational age of 32 weeks
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Ability to swallow own secretions
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Stability outside the incubator for at least 10 minutes
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Tolerance to kangaroo care, which increases breastfeeding incidence, duration, and milk volume
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Episodes of short wakeful periods
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Stable body temperature outside the incubator
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Presence of coordinated suck and swallow reflex.
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