Starting solids at 4 months: what to know

What the guidelines say

Health bodies on both sides of the Atlantic aim for about 6 months:

• WHO: breast milk only for the first 6 months, with safe solid foods introduced from 6 months.
• NHS: start solid foods when your baby is around 6 months old. It adds: “Unless a health visitor or GP tells you to, avoid giving your baby solid foods before they are 6 months old.”
• CDC and AAP: the CDC says the Dietary Guidelines for Americans and the AAP recommend introducing foods other than breast milk or formula at about 6 months, and that introducing foods before 4 months is not recommended. The AAP recommends breast milk only for about the first 6 months.

So 4 months is the earliest limit, not the target. NHS trust guidance is firm on the floor: Frimley Health NHS Foundation Trust says “Do not introduce solids before four months (17 weeks),” and Royal Berkshire NHS Foundation Trust says solids should not be given before 17 weeks because a baby’s gut isn’t ready.

Why around 6 months is the aim

The NHS gives these reasons to wait until around 6 months:

• Breast milk or first infant formula gives your baby all the energy and nutrients they need until then (apart from vitamin D in some cases).
• For breastfed babies, breast milk alone up to around 6 months helps protect against illness and infection.
• Waiting gives your baby time to develop so they can cope fully with solid food, including purées and cereals.
• At around 6 months, babies are better at feeding themselves and moving food around their mouth, chewing and swallowing. They may move on to mashed, lumpy and finger foods more quickly, and may not need smooth purées at all.

The WHO says: “If complementary foods are not introduced around the age of 6 months, or if they are given before this age, growth may falter.” (Complementary foods are the solid foods and drinks a baby has alongside breast milk or formula.) One AAP parent page notes that babies who start solid food too early are more likely to be overweight or obese later.

Starting solids won’t help your baby sleep through the night (NHS). If your baby seems hungrier, the NHS says a little extra milk sometimes helps until they’re ready.

Why “4 months” comes up

• Labels. Some baby food jars and pouches say “from 4 months.” The NHS says to wait until around 6 months even if the label says 4.
• Weight cues. The AAP’s starting solids page lists size as one question to consider: babies who have doubled their birth weight (typically at about 4 months) and weigh about 13 pounds or more may be ready. Size alone isn’t enough: your baby also needs the developmental signs below.
• Allergy prevention. For some babies at high risk of peanut allergy, US guidelines suggest peanut as early as 4 to 6 months (see below).
• Medical reasons. Royal Berkshire NHS Foundation Trust notes that a doctor or dietitian may advise starting earlier than 6 months for medical reasons, for example a baby born prematurely or who needs extra help meeting their nutritional needs.

The readiness signs

Whatever your baby’s age, look for these signs together. The NHS lists three: they can stay sitting up and hold their head steady; they can look at food, pick it up and put it in their mouth themselves; and they swallow food rather than spitting it back out. The CDC adds opening their mouth when food is offered, and moving food from the front to the back of the tongue to swallow.

If your baby pushes food straight back out onto their chin, the AAP says they may not yet be able to move it to the back of their mouth, and suggests waiting a week or two and trying again.

The NHS says these are not signs of readiness on their own: chewing fists, waking more at night, and wanting extra milk feeds. See is my baby ready for solids?

What to talk about with your doctor

If you’re thinking of starting before 6 months, talk to your pediatrician or health visitor first. Questions worth asking:

• Is my baby showing the developmental signs, and are they growing well on milk alone?
• Is there a medical reason to start early, or to wait?
• Does my baby need a vitamin D supplement, or iron? (The AAP suggests checking with your doctor about both during the first year.)
• If my baby has eczema or a food allergy, how and when should we introduce peanut and egg, and is testing needed first?
• If my baby was born early, should we go by corrected age? See starting solids with a premature baby.

If your doctor agrees to an earlier start

• Start smooth. Royal Berkshire NHS Foundation Trust says that if you introduce solids before 6 months, begin with smooth, runny purées, because your baby has only fed by sucking until now. It says to mix first purées with breast milk or your baby’s usual formula. The NHS says cow’s milk can go into food from around 6 months, so don’t use it before then.
• Start tiny. The AAP suggests half a spoonful or less, and giving a little breast milk or formula first so your baby isn’t frustrated.
• Keep milk feeds going. Breast milk or formula is still the main source of nutrition.
• Don’t put cereal in a bottle. The AAP says your baby could choke. Only do it if your doctor recommends it for reflux.
• Follow your baby’s lead. If they cry or turn away, the AAP says not to make them eat. See spoon-feeding responsively.
• No honey, salt or sugar. The usual first-year rules still apply: no honey before 1 year, and no added salt or sugar (NHS).

Allergens for babies at high risk

The 2017 US addendum guidelines on preventing peanut allergy, from an NIAID expert panel, sort babies into three groups:

• Severe eczema, egg allergy, or both: introduce peanut-containing food as early as 4 to 6 months. The panel strongly recommends considering allergy testing first, and some babies have their first peanut in the doctor’s office.
• Mild to moderate eczema: introduce peanut around 6 months, usually at home.
• No eczema or food allergy: introduce peanut freely, together with other solid foods.

In every group, other solid foods should come first, to show your baby is developmentally ready. Peanut is only ever given in a safe form, such as smooth peanut butter thinned into food, never whole nuts. The AAP says babies with severe, persistent eczema or a previous allergic reaction should see their pediatrician first. In the UK, the NHS says to talk to your GP or health visitor before introducing allergens if your baby has eczema or a food allergy, or there’s a family history of allergies. See how to introduce allergens and eczema and starting solids.

Trouble breathing or wheezing, lips or mouth that suddenly swell, swelling of the tongue or throat, a baby who turns pale or floppy, or signs in more than one part of the body at once (such as hives with repeated vomiting) after eating is an emergency. If your baby has an epinephrine (adrenaline) auto-injector, use it first, then call. Call 911.Call 999.Call your local emergency number (such as 112 in Europe or 000 in Australia). Keep your baby lying down, never standing or walking (on their side if they’re vomiting, head and shoulders a little raised if breathing is hard), and go to hospital even if they seem better. See signs of anaphylaxis.

Where US and UK advice differs

• How firm the 6-month line is. US advice (CDC, AAP) says about 6 months and not before 4 months, and the AAP’s readiness questions include reaching double birth weight, typically at about 4 months. The NHS says around 6 months, and to avoid solids before then unless your health visitor or GP advises it. NHS trust guidance names 17 weeks as the absolute earliest.
• Peanut for high-risk babies. US guidelines recommend peanut as early as 4 to 6 months for babies with severe eczema or egg allergy, after a doctor’s assessment. NHS pages introduce allergens from around 6 months and ask families with eczema or allergies to talk to their GP or health visitor first.
• Foods to avoid before 6 months. Some UK leaflets, such as Northern Ireland’s nidirect, still say that if you start before 6 months you should avoid wheat, nuts and seeds, fish and shellfish, and soft or unpasteurized cheeses. That differs from the US approach for high-risk babies, so if your baby is starting early, ask your doctor which allergens to offer and when.