New Study Reveals Baby's IQ Linked to Weight Gain: The Importance of Breastfeeding

How smart is your baby? It turns out that you may be able to tell just by his weight. Scientists have discovered that weight gain and increased head size in the first month of a child's life is linked to a higher IQ at early school age.

Previous studies have shown an association between early postnatal diet and IQ. This study, though, is the first of its kind to focus on the IQ benefits of rapid weight gain in the first month of life for healthy newborn babies. In order to actually examine the potential link between weight and IQ, the scientists followed newborn children until they were six years of age.

"Head circumference is an indicator of brain volume, so a great increase in head circumference in a newborn baby suggests more rapid brain growth," said Lisa Smithers from the University of Adelaide's School of Population Health in a news release.

The scientists made sure to weigh and measure the babies and then tested their IQ later in life. It turned out that babies who put on 40 percent of their birthweight in the first four weeks of their lives had an IQ that was 1.5 points higher by the time they were six. That's compared with babies who put on only 15 percent of their birthweight.

"Overall, newborn children who grew faster in the first four weeks had higher IQ scores later in life," said Smithers. "Those children who gained the most weight scored especially high on verbal IQ at age six. This may be because the neural structures for verbal IQ develop earlier in life, which means the rapid weight gain during the neonatal period could be having a direct cognitive benefit for the child."

Most weight in a baby's first month is gained through breastfeeding. In fact, previous studies have shown that breast milk is ideal for infants, possessing the perfect mix of vitamins, protein and fat. It contains antibodies that can help babies fight off viruses and bacteria, and it can also reduce a child's risk of developing asthma or allergies, according to WebMD. It's not surprising that proper breastfeeding can also increase a child's IQ.

The study doesn't just show an interesting correlation between IQ and weight, though. It also shows the importance of making sure babies are fed properly in general. It could have major implications for poverty-stricken areas where children are sometimes not able to receive the nutritional benefits that they need, especially when a mother has difficulty breastfeeding her child.

"We know that many mothers have difficulty establishing breastfeeding in the first weeks of their baby's life," said Smithers. "The findings of our study suggest that if infants are having feeding problems, there needs to be early intervention in the management of that feeding."

The findings are published in the journal Pediatrics.