Last week news of a study evaluating the timing of solid food introduction for infants emerged. It got a ton of press because the study evaluated the timing of solids on the likelihood of obesity at 3 years of age. Researchers divided babies into 2 groups, those that received partial or full breast milk until 4 months, and those that were weaned from breast milk and received formula exclusively before 4 months of age. Researchers then determined when babies were given solid food (rice cereal, biscuit, pureed “baby” food, etc) of any kind.

The results proved notable. Babies who received exclusive formula and solid foods before 4 months of age were 6 times more likely to be obese as a 3 year-old (defined as BMI over 95%, sum of triceps and subscapular skinfolds). This however, was not true for the babies that were receiving breast milk of any kind. So this study may not be applicable to many babies; in the US for example, 25% of infants are never breastfed and approximately half are breastfed for less than 4 months. Yet still, this sheds light on what we can do to help. Use this data when Grandma Trudy is urging you to feed your infant cereal at 3 months. Or why it’s best to wait until 4 months when you get excited about starting solids. Those of you who didn’t wait? Before you spin your wheels with worry about that bite of rice cereal you gave your baby at 3 1/2 months, read on. Because although, if it were my child, I wouldn’t give baby food before 4 months, there may be more to consider when it comes to timing.

Study Design and Results:

  • 847 babies enrolled in the study and were divided into two groups: those with exclusive formula feeding (33%) or those with breast milk feeding or partial breast milk feeds (67%). There was no explanation if they asked moms about pumping milk or how they were giving breast milk. From my read of the study, if a baby had any breast milk at all until 4 months of age they were in the breast-feeding group. This is a unique take; most studies do the opposite. That is, they include babies in the breast milk group if exclusively breast feeding and put partial or mostly formula-fed babies in the formula group.
  • The primary focus of the study was on the timing of introduction of solid foods categorized as <4 mo, 4 to 5 months and >6 months of age to the outcome of obesity at age 3.
  • Researchers evaluated effect of maternal race, ethnicity, age, education and household income on choices to breast feed or formula feed. Mothers reported their prepregnancy weight and height. Researchers evaluated gestational age, birth weight, birth height, and controlled for change in weight between 0 and 4 months of age because of the suspicion that, “Mothers may perceive rapidly growing infants as requiring solid food supplementation in addition to breast milk or formula.”

The Study Results:

  • Formula-fed babies that received food before 4 months of age were 6 times more likely to be obese as a 3-year old compared to those that didn’t get solid food (anything but formula) before 4 months.
  • There was no effect on breast-fed babies in regards to early introduction of solids before 4 months and obesity risk.
  • Interestingly, breastfeeding status was associated with timing of intro to solid foods. Only 8% of breast-fed babies, compared with 33% of formula-fed infants, started solids early, before 4 months.
  • Like many studies before, breast-fed babies were less likely to be obese at age 3. A reminder that breast feeding may be a great, protective measure to avoid increased risk of overweight and obesity. For mom, too!

So okay, what to do with this? Know that there is little benefit to starting solids before 4 months of age. Previous studies have found that babies who were started on solids prior to 4 months of age were also worse sleepers. Read my blog post about rice cereal introduction and sleep.

Tips on Introduction of Solid Foods and Obesity Risk:

  • Breastfeed a baby if possible. In addition to the immune protection, maternal effects, and economics, breastfeeding really may be protective against obesity. That’s a huge win! So why didn’t breast fed babies have the same risks when getting solids before 4 months of age? Researchers theorized that breast feeding may promote self-regulation of an infants’ energy intake, and that mothers may learn to recognize hunger cues differently in breast-fed babies. Because of this, they felt breast-fed babies didn’t have the same increased risk of obesity when started on solids early (<4 months of age) like the formula fed babies.
  • Start solids after 4 months of age, particularly if your baby is formula fed. There is no great data to support early introduction of solids. Remember, rice cereal doesn’t help babies sleep through the night, despite the myth…
  • I generally recommend starting solids at 6 months of age. However, new recommendations from the AAP Committee of Nutrition suggest that starting iron-fortified cereals at 4 months of age, particularly in breast fed infants, can protect against iron deficiency.
  • If your baby is slow to take pureed foods, even at 6 months, don’t worry. In this study, there was no association with risk of obesity for babies that delayed introduction of solids even after 6 months.
  • Remember that consensus is hard to find in most any medical decision. The AAP recommends delaying introduction of solids to at least 4 to 6 months of age while the World Health Organization recommends solid food introduction only at 6 months of age to promote exclusive breastfeeding. Talk with your baby’s pediatrician if you get confused by these recommendations…