While the benefits of breast milk are established, a new study revealed the method of feeding also makes a difference. Findings showed feeding straight from the breast could be more beneficial for babies' weight compared to giving them breast milk out of a bottle.

The study titled "Infant Feeding and Weight Gain: Separating Breast Milk From Breastfeeding and Formula From Food" was published in the journal Pediatrics on Sept. 24.

The researchers examined data on more than 2,500 pairs of mothers and infants, comparing their feeding methods in the first year of life. Breastfeeding was found to be the healthiest method, linked to a lower body mass index.

Overall, the babies who continued to be exclusively breastfed at the age of six months had the healthiest weight by the age of 12 months. On the other hand, babies who were fed formula (i.e. not exclusively breastfed) at six months had a three-fold higher risk of being overweight by their first birthday.

Furthermore, when examining babies who consumed breast milk, it was found those who were fed with pumped breast milk were likely to weigh slightly more than those fed directly from the breast.

"Moms who pump go through a lot of effort to do that, and I wouldn't want them to get the impression that it's not worth it," assured study author Meghan Azad, a research scientist at the Children's Hospital Research Institute of Manitoba. "But it does raise the question of, if pumped milk is not the same or not as good, why is that?"

The slower and healthier weight gain for the baby, she suspected, may have to do with the range of "interesting enzymes and hormones" found in breast milk. When the milk goes through the process of pumping, freezing, and thawing, it was possible their activity was somehow weakened.

Another possible reason Azad offered was better self-regulation as a result of feeding. This was because "breastfed infants learn to stop feeding when they are full, whereas bottle-fed infants, regardless of what is in the bottle, are often encouraged to empty the bottle, and do not regulate their own milk intake," she explained.

Guidelines from the World Health Organization recommended exclusive breastfeeding for the first six months of life. At this stage, complementary foods were introduced to meet the babies' increased demand for nutrients.

The study also found a risk of rapid weight gain associated with these foods being introduced before the age of five months. The best period, the researchers stated, was sometime after the five-month mark but before the seven-month mark. This not only offered benefits of healthy weight gain but also allergy prevention and infectious disease prevention, Azad noted.