The ability to obtain the nutrients our bodies need is often taken for granted. In actuality, obtaining nutrients by sucking is the most complex task of infancy and can be especially challenging for preterm infants who have a history of intubation, continuous positive airway pressure and nasal cannulation due to respiratory distress syndrome.

"It is the most complex task of infancy because it is a combination of several processes that must be precisely coordinated - sucking, swallowing and breathing," explained Jacqueline M. McGrath, PhD, RN, FNAP, FAAN, associate professor at Virginia Commonwealth University, Richmond. "If one area fails, than the whole process fails and one of those skills - breathing - has immediate consequences for the infant."

In cases where the process is failing, nurses might need to insert invasive breathing tubes down the baby's throat, along with feeding and oxygen tubes taped to the baby's nose and face. This might significantly delay the regular progression of feeding.

"In one case, we had an infant born at 34 weeks who was physiologically stable, but just did not want to suck," explained Barbara Medoff-Cooper, PhD, CRNP, RN, FAAN, professor in pediatric nursing and director of the Center for Biobehavioral Research at the University of Pennsylvania, Philadelphia. "The mother wanted to put the infant to the breast but nothing was happening. The nurses worked with the mother over a week to help her support her infant, slowly increasing his intake from a nipple and decreasing the use of the nasogastric tube for feeding."

It was a slow process, with some successes and some failures, said Medoff-Cooper, who also is the Ruth M. Colket professor of pediatric nursing at the Children's Hospital of Philadelphia, but eventually the infant began to suck more vigorously and he was finally ready for discharge when he was almost 36 weeks gestational age.

Many babies with respiratory distress syndrome who cannot competently feed orally may be delayed in the NICU for some time or required to continue tube feedings at home through a gastric tube. In the worst cases, children may not learn to take nourishment orally for months or even years.

Brain Development

This issue is a priority not only because it delays a baby's release from hospital, but also because it may say something about the baby's brain development down the road.

"Sucking does give us a window into how the brain is developing," McGrath said. "It is a task that babies are learning, to some degree. For the full-term infant, we think of it as intrinsic, but for the preterm infant that isn't the case. They're learning it through the right opportunities and experiences, provided when the baby is alert and ready."

"From the world of developmental delays, we do know infants with known significant neurologic insults or major developmental delays often have feeding problems and speech issues," Medoff-Cooper added.

Providing the right experience at the right time is key, as many experts say this learning process cannot be forced. Unfortunately for many frantic parents, they might try propping up a baby's chin, feeding more often or for long periods of time, or using a faster flow nipple (which often can be detrimental to the baby who has poor coordination of the suck/swallow/breathe process).

"Nurses advise parents to use infant cues during feeding. If an infant starts out feeding well and then stops, has a change in heart rate or respiratory rate, or has a decrease in muscle tone, then they should stop feeding," Medoff-Cooper said. "They may need to give the infant a rest, but they should not try to force an infant to feed by holding the cheeks together, propping up the chin, or feeding through an increased respiratory rate or decreased heart rate."