Quick Facts
| Age | 20 weeks (almost 5 months) |
| Length | ~60–70 cm (WHO range, ~5 months) |
| Weight | ~5.4–9.3 kg (WHO range, ~5 months) |
| Daily Sleep | ~14–16 hours (about 3 naps + longer nights) |
| Feedings per Day | Feed on cue |
| Formula Amount | On cue — follow your formula’s feeding chart |
Length and weight are the WHO 3rd–97th percentile range (both sexes) from the WHO Growth Charts for Canada. Your provider tracks your baby’s own growth on these charts.
Key Takeaways
At 20 weeks, most babies have the 3-month skills the Canadian Paediatric Society describes and are building steadily toward the next set.
Physical Development
A 20 week old baby has strong head control and often sits propped with support, and rolls from front to back, per the CPS milestones. Trunk strength is building toward sitting on their own, which the Canadian Paediatric Society lists among the end-of-8-months milestones. During tummy time, many babies push up on their hands and pivot to look around.
Which means the floor is now your baby’s territory. Get down on your hands and knees and look at each room from that height — dropped coins, pet food, trailing cords, uncovered outlets. Button batteries deserve their own mention: they’re in remotes, key fobs, greeting cards and bathroom scales, and if swallowed they can burn through tissue within hours. Any suspected swallow is an emergency room visit, not a wait-and-see.
Hands & Hand-Eye
A 20 week old baby reaches for and grabs objects with more control and brings hands and toys to the mouth, per the Canadian Paediatric Society. This is the groundwork for holding and shaking a toy and passing objects hand to hand, which the CPS describes by the end of 8 months. Offer safe, easy-to-grip toys of different textures.
Social & Communication
A 20 week old baby smiles, laughs, squeals and babbles, and “chats” back and forth, per the Canadian Paediatric Society. Copying speech sounds and responding to others’ emotions come over the following months, among the CPS end-of-8-months milestones. Respond to the babble and name what your baby looks at. Videos marketed as educational won’t do this job — babies this age learn language from back-and-forth with a person, and the CPS advises no screen time before age 2.
DEVELOPMENT & PLAY
- Offer supported sitting with cushions or your hands, always on the floor and always close by, so your baby can practise balance and take in the room. A propped baby topples sideways without warning — on a sofa or bed, that’s a fall.
- Offer safe, grippable toys of different textures to reach for, grab, shake and safely mouth. If teething is starting, a solid silicone or rubber teether is the safe option — skip amber teething necklaces and bracelets. Health Canada warns against them: the cord is a strangulation risk and the beads a choking one, and there’s no evidence they relieve pain.
- Keep up daily, supervised tummy time to build trunk and shoulder strength for sitting.
- Keep small objects, cords and choking hazards out of reach, and never leave your baby alone on a raised surface.
ROUTINES & SLEEP
- Lean into the three-nap rhythm the CPS describes, with a calm, consistent wind-down.
- Keep days bright and active, nights calm and dim.
- Practise safe sleep every time, and keep starting your baby on their back even once they can roll. If your baby rolls onto their front on their own, you don’t need to turn them back — that’s safe once they can get there under their own strength. Your job is the starting position and a bare crib; the rest is theirs.
FEEDING & HEALTH
- Keep feeding on cue; follow your formula’s feeding chart for amounts.
- Give breastfed babies a daily 400 IU vitamin D supplement, per Health Canada and the CPS. Combination-fed babies need one too — they don’t take enough formula to cover the requirement. Exclusively formula-fed babies usually don’t, since vitamin D is already added to formula.
- Solids are coming soon — but wait until around 6 months. We’ll cover readiness signs in the weeks ahead.
Frequently Asked Questions
What should a 20 week old baby be doing?
A 20 week old baby usually has strong head control, often sits propped with support, rolls front to back, grabs objects with growing control and brings them to the mouth, and is vocal and giggly — smiling, laughing, squealing and babbling, per the Canadian Paediatric Society. Every baby develops at their own pace; raise concerns, especially in more than one area, with your doctor.
When can babies sit up?
Many babies sit with support around this age and build toward sitting on their own, which the Canadian Paediatric Society lists among the milestones most babies reach by the end of 8 months. There’s a wide normal range. Practise supported sitting with cushions or your hands, always staying close, and keep up daily tummy time to build the strength behind it.
Can I start solids at 5 months?
The Canadian Paediatric Society recommends waiting until around 6 months before introducing solids. Before then, breast milk or infant formula meets all your baby’s needs, and their digestion and head control aren’t fully ready. Watching you eat, mouthing hands or waking more don’t mean your baby is ready. We’ll cover the readiness signs in the coming weeks.
How much should a 20 week old baby eat?
A 20 week old baby feeds on cue — the Canadian Paediatric Society advises feeding on demand. Amounts vary a lot; follow the feeding chart on your formula’s packaging. Plenty of wet diapers and steady weight gain show your baby is getting enough. Solids aren’t recommended until around 6 months.
How much sleep does a 20 week old need?
By 4 months, the Canadian Paediatric Society notes, most babies need three naps a day — morning, afternoon and early evening — with total sleep around 14–16 hours across naps and nights. Every baby differs, and night waking still happens. A regular daily rhythm and calm wind-down help sleep settle.
100% European Certified Organic Formulas
Express delivery for FREE (for 4-packs and up)
Shop organic formulas
