Quicker Infant Growth Tied to Higher IQ Later
But difference in scores was fairly small in study of full-term babies
"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 U.S. expert said.
"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 pediatric 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.