Advances in Nutrition review notes that most preterm infants catch up to full-term infant growth patterns within three years

“Several myths surround the growth of preterm and small infants,” according to Expected and Desirable Preterm and Small Infant Growth Patterns, the scientific review published in Advances in Nutrition: An International Review Journal, a publication of the American Society for Nutrition. According to the authors, Dr. Tanis R. Fenton et. al., these myths are “often founded in the prevalent misconceptions that fetal and infant growth patterns solely and strongly predict future risks of obesity, cardiovascular disease, and metabolic disorders.”

In order to dispel these myths and shed an objective light on the subject, this review examined the full spectrum of infant growth expectations, focusing on how preterm infants’ growth may be similar to or different from full-term infants’ growth. Moreover, the authors emphasized how science should inform how nutritionists and healthcare providers talk to and counsel parents.

A common concern among neonatologists has been that if the diets and treatment plans for preterm and small infants lead them to grow too quickly, catching up to the growth expectations for full-term babies, they will have higher risks of obesity and cardiovascular disease in later life. This review, however, found that preterm and small infants are not necessarily at higher risk for obesity and cardiovascular disease in the long term, but rather “the long-term risks for obesity and cardiovascular disease is influenced by a combination of modifiable and nonmodifiable factors, including genetics, social determinants of health, prenatal history and nutrition, as well as later life lifestyle choices, including physical activity, nutrition and energy balance.”

Adequate nutrition and growth are both necessities for neurodevelopment. However, just as the authors pointed to a more complex relationship between preterm infants and obesity and cardiovascular disease, they also pointed to a similarly complex relationship between preterm infants and long-term neurodevelopment. According to the authors, “in neonatal intensive care units that provide good nutrition support as well as nutrition services post-discharge, the causes of poor cognitive outcomes are less likely mediated by poor growth as there are other more influential directly contributing causes.”

An editorial accompanying this review, Revolutionizing Neonatal Nutrition: Rethinking Definitions and Standards for Optimal Care, noted how the review “significantly contributes to our understanding of growth patterns in preterm infants and provides valuable guidance to rethink definitions and standards for optimal nutritional care.” In particular, the author of the editorial, Ariel A. Salas, notes that “the call for the development of individualized growth trajectories due to multicausality in growth outcomes is insightful.”

Individual growth variability is a biological phenomenon influenced by genetics, prenatal growth, morbidities, and nutrition. Thus, it is important to recognize that preterm and full-term infants with healthy outcomes exhibit a wide range of growth variability. Nonetheless, the authors recognize that parents are concerned about children who plot low on growth charts. They stress the importance of avoiding the commonly used word “failure” when discussing an infant’s growth. Even if an infant’s growth is faltering, it can be very harmful and alarming for parents to hear the word “failure” about their child. Similarly, it can be harmful for parents and children to hear the words “obese” or “fat” when used to describe their family member or themselves. Finally, the authors stress that “no specific percentile should be set as a growth goal; individual variability should be expected.”

Overall, “while there may be some challenges and concerns related to preterm growth during the neonatal period, these risks are not necessarily predetermined by an infant’s preterm birth or neonatal intensive care unit course.” In fact, the majority of uncomplicated preterm infants tend to catch up in head circumference, weight, and length measurements between 0 and 36 months.

If you’re interested in learning more about this review and delving more deeply into the many factors that can influence infant growth and health outcomes throughout the lifespan, tune into Dr. Tanis Fenton on Desirable Preterm Infant Growth Patterns. This podcast is Episode Two of the recently launched podcast series Advances in Nutrition: An International Review Journal—The Podcast.

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