Pros and Cons of starting solids at 4 months vs 6 months

Pros and Cons of starting solids at 4 months vs 6 months

Since 2002, the World Health Organization and Health Canada have recommended that babies start solid food around six months of life. Before 2002, we were encouraged to start our babies on complementary foods between four to six months. The change to six took a while to catch on with doctors and parents.

Most moms seemed to be waiting until six months to introduce solid food, as recommended up until a year or two ago. It now seems to be changing again!

Lately, I’ve been noticing a trend of starting solids earlier again. Like between 3-5 months. Usually, the mom will reference “new research about introducing allergens.” Or their doctor recommended starting foods early to prevent allergies. For all babies.

Is this true? What are the pros and cons of starting solids at four months vs six? Read on to find out!

Can starting solids early prevent allergies?

The most recent Canadian recommendations on when to start allergenic foods are from the 2019 Canadian Pediatric Society. They published a document titled “Timing of introduction of allergenic solids for infants at high risk.”   For babies at low or no risk of food allergy, they continue to recommend introducing solids at about six months. This is when most babies show signs of readiness and require extra sources of nutrition to bump up iron stores.

The document defines ‘high risk’ as a baby that has a history of food allergies or a parent/sibling with a food allergy. It’s still recommended to start common allergens at six months (but not before four) for high-risk babies.

And the World Health Organization has new complementary infant feeding guidelines published in late 2023. They did a deep dive (starting on page 21 of this 221-page document called “Optimal Timing of Introduction of Complementary Feeding: A Systematic Review and Meta-Analysis.”) They came to the conclusion that there’s no benefit to starting solids (including high-risk allergens) before six months.

So where does this 4-month thing come from? In 2017, in the United States, the National Institute of Allergy and Infectious Disease (NIAID) published a document called: Addendum Guidelines for the Prevention of Peanut Allergy in the United States.

Specifically, in relation to peanut allergy, the guidelines suggest:

For infants with eczema, egg allergy or both, consider testing for peanut allergy before introducing peanuts into the baby’s diet. Based on test results, the earliest age of peanut introduction is four to six months.

For infants with mild to moderate eczema: the earliest age of peanut introduction is recommended as “around six months.” For infants with no eczema or any food allergy, the earliest age of peanut introduction is: “Age-appropriate and in accordance with family preferences and cultural practices.”

The Candian Society for Clinical Allergy and Clinical Immunology also endorsed the guidelines: “The “take-home” messages include that peanut products should be introduced early in the first year of life, and for the majority of infants, peanut can be introduced at home.”

So, the newest recommendations encourage parents not to delay introducing peanuts and other high-risk allergens (eggs, wheat, dairy, tree nuts, soy). Compared to the early 2000s, it was thought best to delay allergens until one to three years. And it’s working!

Peanut allergy prevalence in 2018-19 was 2.6% compared to 3.1% in 2007-11, a 16% decrease. So now we know that introducing high-risk allergens can help prevent the allergy rather than cause it. But somehow, this recommendation to start allergens around six months has gotten warped to starting allergens for all babies at four months. This is not what is actually recommended, as you can see above.

Latest research on when to start solids: allergenic foods

Only one randomized controlled trial and expert opinion from 26 professional organizations supported the 2017 NIAID recommendation. What sole trial informed the NSAID recommendations to start peanuts at four months potentially? 

The LEAP “Learning Early About Peanut Allergy” (LEAP) study. 

The study included 640 babies, half of whom started eating peanuts early and regularly (starting between 4 to 11 months). The other half tried peanut protein for the first time later (5 years). All participants were at higher risk for allergies, defined in this study as having a known egg allergy, severe eczema or both. 

The study found that 2% of children who started peanuts early had an allergy. The group that avoided peanuts until late had higher rates of peanut allergy: 14%.

One important thing to note is that the average age of starting the LEAP trial in the “early introduction” group was 7.8 months. Not four months.

However, some other research has examined whether an introduction before six months might be beneficial.

The EAT (Enquiring about tolerance) study:

The authors of this study hypothesized that starting solids before 3-4 months may actually increase allergy risk. Possibly because the bacterial colonization hasn’t been completed to improve immunity or the gut is too ”leaky.”

To test this, the researchers included breastfed infants from the United Kingdom. Half of the babies were introduced to peanuts, cooked eggs, cow’s milk, sesame, whitefish, and wheat at about three months of age. The other half was to start these allergenic proteins as normally recommended at six months. 

They found there was no significant difference in the number of children with a food allergy at age 3, whether they started these highly allergenic foods at either 3 or 6 months.

However, these results could be inaccurate because many of the early-introduction groups didn’t successfully follow the study design. When looking at the smaller group of participants that were able to introduce the six allergens at three months, they found a lower risk of food allergy for the early introduction group compared to the 6-month introduction group (2.4% vs. 7.3%). This was for eggs and peanuts only, not the other allergens.

But only 31.9% of all the babies in the early-introduction group were successful at starting the allergens early. Compared to over 80% in the standard introduction group. My own interpretation of this is that it’s difficult to feed a 3-month-old, as they’re not developmentally ready for solids yet!

Besides age – when is my baby ready to start solids?

While age is one indicator of when to start solids, there are other things to watch for, too.

Beyond physical strength, what are some other signs babies are ready to start solids?

Physical Strength:

“My baby is six months or older and doesn’t sit unsupported, so I’m not feeding him solids yet.” There seems to be this myth that the baby needs to sit independently for a minute, two minutes, maybe five minutes – before starting baby-led weaning or self-feeding. I’m not sure where this came from. Even Gill Rapley, the creator of the term “Baby Led Weaning,” has an article on her website where she explicitly states there’s NO “60-second rule”.

Two of my own babies didn’t sit fully unsupported on their own for any length of time until they were eight, maybe closer to nine months. But they were able to self-feed before this age. I’ve also confirmed this with the Occupational Therapist that I work with: Baby does not need to sit unsupported on their own before starting solids.

They do, however, need to be able to sit with support. Your baby needs enough strength in their trunk or body and neck. So that when they are seated supported in a highchair, they can lean forward to grasp food and get it to their mouth without needing their arms for balance. And they need to be able to lean forward and spit food out if needed. If they don’t have the strength to lean forward and are just in reclining mode, that can be a choking hazard.

So what about the “support” if you find the highchair isn’t supportive enough for your baby and they’re leaning to one side? You can roll up towels and place them either on either side of your baby or one side of them, even under their bum if they’re not high enough. The highchair tray or table should come between about their nipple and their belly button. And their feet should be supported as well, to help them to be able to self-feed.

So even if your baby has just turned six months and can’t sit fully unsupported, they should have enough physical strength to self-feed. If that’s supported, that’s okay. If they don’t yet even have that strength, they may not be quite ready, and it’s okay to start with purees.

Interest in Eating

Your baby is probably putting everything in their mouth. Including toys and their hands. That’s actually preparing them to start solids and feed themselves. If your baby’s really eager to eat but not quite six months yet, you can sit them at the table with you during meals. Give them something to chew on, even if it’s just a plastic spoon. They get to practice moving that around in their mouth and decrease their gag reflex so they are more prepared to eat.

Loss of extrusion reflex

The first few times you start solids (especially if your baby isn’t six months yet), they may push the food back out with their tongue. This is called the extrusion reflex and is needed for sucking. Often, they will figure it out after a few times of being offered solids, and start eating.

But if your baby continues to do this, perhaps they’re just not ready to chew and swallow food and still focused on sucking up that milk!

What about a large or small baby?

Often, I hear: “My baby’s big. I need to start solids early.” Or “My baby’s really small. I need to start solids early.” Neither of those are good reasons, on their own, to start solids. Your milk is more nutrient-dense than any of the starter foods your baby will be eating anyway.

There are a few reasons why you may need to start solids early, on the recommendation of your doctor, such as reflux. But in that case, you’d likely be starting with purees.

When can I start Baby-led Weaning or finger foods?

Many of the same indicators apply if you skip purees and use baby-led weaning. Age, physical strength and interest are some signs of readiness to watch for. And keep in mind that Health Canada recommends introducing finger foods along with purees right from the start!

Pros and cons of starting solids at four months

Pros of starting early

1. It may help with reflux for babies suffering.
2. Research is not conclusive as to whether it will help prevent allergies in high-risk babies.

Pros of waiting until six months:

1. It’s easier. Sure, starting solids is an exciting new step – but also extra work and cleanup!
2. It’s the official recommendation from the World Health Organization, Health Canada, the Canadian Paediatric Society and Dietitians of Canada.
3. It allows your baby full benefits of breast milk – protection from immunoglobulins and gut bacteria.
4. Your baby will have developmental readiness and interest in solids. Often, the extrusion reflux of their tongue just pushes solid foods back out of the mouth until close to six months anyway.
5. Starting solids before four months may actually increase risk of allergies and has not conclusively been shown to decrease allergies (yet, anyway).
6. Babies are more likely to be affected by Foodborne Illness or contaminated foods the younger they are. Waiting until six months gives their gut and body more time to develop.

Want more info about how to start solids using Baby-led Weaning? Click here to register for my free webinar “How to get started using Baby-led Weaning.”

My final opinion? Is it better to start solids early to prevent allergies?

So there may be a small benefit in terms of allergy prevention to start solids “early.” It’s too early to say that with confidence. But even so, it might not be practical for most babies to start solids before six months. Especially if you want to do baby-led weaning or self-feeding. Under six months most babies will not be developmentally ready.

Another point to consider is that the current recommendations from the World Health Organization (and all government health organizations in developed nations) support exclusive breastfeeding up to 6 months of age. Human milk is protective against allergies for the breastfed baby.

Maybe future evidence will more strongly support the introduction of allergens before six months in high-risk infants. For now, if you have a high-risk baby, discuss with your allergist whether early introduction of solids may be beneficial.

But for all babies (including those at high risk for an allergy), introducing peanuts at six months of age fits within the current guidelines recommending starting solids and allergens at that time.

 Jennifer House is a Registered Dietitian, author & mom of 3. From Baby-led weaning to picky eating and meal planning, she helps you to make feeding your family easier.