Understanding How Preemies Grow

Preterm and underweight babies show better development with better growth

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Sometimes babies arrive earlier than expected. They may also arrive a lot smaller than expected. What does this mean for their development?

A recent study found that children's weight gain and growth in head circumference can provide clues to their IQ five years later.

The most critical period for growth in these children appears to be the time frame when they would have been born in a normal pregnancy, if not born early.

In other words, that time period includes however many weeks old the child is when the mother would have been 36 to 40 weeks pregnant.

"Ask your pediatrician about your preemie's nutritional needs."

The study, led by Marika Leppänen, MD, o the Department of Pediatrics at the University of Turku in Finland, looked at the cognitive development of babies born before their due date.

Cognitive development refers to a child's brain development.

The researchers followed 181 children who were either born weighing less than 3.3 pounds or were born before the 32nd week of pregnancy.

Weighing less than 3.3 pounds is considered being "small for gestational age," or underweight, because the child weighs less than normal even for the pregnancy week when they were born.

The children's weight, length, and head circumference was measured nine times between when they were born and when they turned 5 years old.

Then the children's IQ was assessed when they were 5 with a test designed specifically for preschool children.

The researchers did not find that how quickly children grew in length or height was related to children's IQ at age 5.

They did, however, find links to IQ related to weight and head circumference among children who were born early but not underweight.

A slightly higher IQ showed up among children who gained more weight or whose head circumference grew faster between birth and age 2.

A similar pattern appeared among underweight babies but only for growth of their head circumference between 36 weeks of gestational age and 4 months old.

Gestational age refers to the weeks the child would have been in the womb. A baby born at 32 weeks of pregnancy would be 36 weeks gestational age one month after being born.

These findings mean that parents and pediatricians may be able to learn more about their child's likely brain development partly based on the child's weight gain and head circumference growth.

The biggest influence on children's later brain development appears to be growth around the time the child would have been born if not born early.

This time refers to when a child is 36 to 40 weeks of gestational age.

Therefore, nutrition during this time period is especially important for children who were born early or early and underweight, the authors suggested.

The study was published December 16 in the journal Pediatrics. The authors reported no conflicts of interest.

The research was funded by the Foundation of Pediatric Research/The South-Western Finnish Foundation of Neonatal Research, the Päivikki and Sakari Sohlberg Foundation and Turku University Hospital.

Review Date: 
December 15, 2013
Last Updated:
December 30, 2013