Babies who gained weight and head circumference more rapidly during the first
month of life scored slightly higher on intelligence tests when they were 6
years old, according to a large new study.
But a baby's early rate of growth didn't influence the child's behaviour
later in life, according to the study.
"We found that faster growth in the first four weeks following birth was
linked to a small increase in intelligence quotient scores at 6.5 years, but
there were no clear effects on children's behaviour," said the study's lead
author, Lisa Smithers, a postdoctoral research fellow in early life nutrition at
the University of Adelaide, in Australia.
She added that these findings suggest that "it is important that parents seek
help for any concerns they might have about their baby's growth or feeding quite
quickly so that any problems can be addressed early".
"[However], we cannot say that faster growth causes a higher IQ," Smithers
said. "It is possible that a phenomenon called 'reverse causality' may be at
play, for example, if children with lower IQs had poorer growth."
The study included about 17 000 mothers and their babies from Belarus. Only
mothers who delivered a single, healthy baby were included in the study. In
addition, the babies were all born at or after 37 weeks of gestation.
Researchers measured the babies' weights and head circumferences over the
first four weeks of life. Intelligence was measured using several IQ scales that
were combined to yield a full-scale IQ score at 6.5 years. The full-scale IQ
scores can range from 50 to 150, Smithers said, and the average score is 100. To
assess behaviour, parents and teachers completed behaviour questionnaires.
Babies with the highest growth in weight and head circumference scored 1.5
points higher on the IQ scale compared to babies with the lowest growth. The
researchers found no statistically significant differences in children's later
behaviour based on early growth.
"Our study involved thousands of healthy babies, so our findings reflect a
wide range of growth patterns that might be expected within a healthy
population," Smithers said.
Researchers accounted for other important factors, such as family income and
parental education, in their analysis.
"The size of the effect we found on children's IQ would not be noticeable to
individuals," Smithers said.
But the results may be important in the bigger picture, a US expert said.
God's perfect food
"A 1.5-point difference would be meaningless in an individual child and that
child's success in life, but on a population level, such a difference may
matter," said Dr Lisa Thornton, medical director of paediatric rehabilitation at
LaRabida Children's Hospital in Chicago.
"It's clear, though, that brain growth equals [thinking ability] growth, and
it's interesting to see that really early brain growth correlates to
intelligence at 6 years," she said. "It shows that it's important that early
feeding difficulties shouldn't linger."
Thornton said women who are having breast-feeding trouble should seek help
sooner rather than later. "Breast milk is God's perfect food, but this study
suggests that it's better to get nutrition early," Thornton said.
Both Thornton and Smithers said this study's findings don't suggest that
parents should overfeed their babies.
"Babies should never be forced to eat," Smithers said. "Babies should be fed
on demand. Overfeeding may raise other problems over the longer term, as there
is some evidence to suggest that more rapid growth in infancy is linked to
poorer health outcomes, such as obesity and high blood pressure. Our study draws
attention to the importance of balance."
Thornton agreed. "Make sure the baby is getting enough food for optimal
growth, but don't overfeed to try to make the baby smarter," she said.
To learn about overcoming breast-feeding problems that could interfere with
early nutrition, visit the US
National Library of Medicine.