Essential nutrients for premature infants

Once a baby is brought into the world, he or she is suddenly without their mother's nutrition that was providing what's needed to build tissues and organs and to create the enzymes and structures that must begin functioning almost immediately.  Healthy full-term infants can usually function well.  Their organs are already at a capacity that's ready to do what they must. They can feed on a mother's breast milk or infant formula and obtain what they need to gain and grow. 

Premature infants need to continue developing their tissues, organs and enzymes.  

In particular, premies need extra protein, calcium, magnesium and phosphorus.  Increased protein improves their growth rates. According to a study by BE Stephens and colleagues (Pediatrics 2009, pages 1337-43), higher levels of protein in the first week increased mental development at 18 months of age for extremely low-birth-weight babies.  For those reasons, most premature formulas include 20 percent more protein. 

A premature infant also misses the calcium, magnesium and phosphorus that are important for bone development and general growth, since they get 80% of those minerals during the last trimester (from the 27th week on) so again it's important that they get them.

While breast milk has low levels of these elements, the absorption is good.  But even with this greater absorption, known as bioavailability, the amount the infant needs is more than breast milk can provide alone.  Therefore, a liquid or powdered human-milk fortifier has additional protein, calcium, magnesium, and phosphorus to add extra.  Formulas designed for premature babies similarly have increased amounts of these nutrients.

Aren't Carbohydrates and Fats Needed too?

Every infant needs carbohydrates and fats to provide the building blocks for all the cells and for a healthy metabolism.  They each provide about half the calories the infant needs as energy and to maintain their body temperature. Premature formulas contain fat blends that include 20% or more of medium-chain triglycerides to ease fat absorption.  

Factors Needed for a Premie's Brain Growth

Docosahexaenoic acid (DHA) is found in omega-3 or fish oils has been shown to increase brain growth and benefit intelligence throughout life. It comes to infant's during pregnancy and breastfeeding in women who eat fish or take fish oils or omega-3 oils. But for premies that can be a problem because most of an infant's DHA is transferred across the placenta in the last trimester. As a result, most international societies want more added to infant formulas to mimic what full-term breastfed babies get. But the amounts of DHA and arachidonic acid (ARA) (the balancing factor babies need) are less consistent. Some formulas have twice as much as others.  

Premies have  low levels of intestinal enzymes

Premature infants also have low levels of the intestinal enzyme that digests lactose in order for it to be absorbed.  34-week infants only have 30% of the enzyme function that full-term babies have.  As a result, formulas for premature infants reduce the lactose to 40-50% of the carbohydrate, balancing that with easily digested glucose molecules.

Iron and Other Vitamins and Minerals

Iron is needed to transport oxygen and to maintain the supply of red blood cells.  Very early premature infants may even require transfusions or a red blood cell stimulator, especially in their first weeks when frequent laboratory tests are needed to monitor their progress.  Fortunately, older premies tolerate iron-fortified formulas well, without any problems or gastrointestinal upset.

Premature infants also need the other minerals and all the vitamins at least as much as full-term infants do.  The minerals become part of different enzymes and cells that a baby must make.  The vitamins are important too, to increase the activity of many of the enzymes. As a result, formulas for premies, both in the hospital and for once they're discharged, have higher levels of many of the vitamins and minerals. 

Catching Up 

It takes a premature infant a long time to catch up in growth and in developing their body structures. It's generally estimated that the extra protein, vitamins and minerals are needed for at least 6 months plus a month for every month they are early. 

So a baby 

• born 4 weeks (or a month) early, 
  • needs the extra nutrients for 7 months (6 + 1 month), 
• and a baby who was 8 weeks early means 
  • they need the extra for 8 months (6 + 2 months),

 whether it's from the fortifier added to breast milk or a special premature formula.