Phase 4 — 6 to 9 months
Solids introduction and mobility
A critical milestone: introducing solid foods. Open window for immune tolerance to allergens. Mobility increases. Separation anxiety begins — a normal sign of cognitive development.
A critical milestone: introducing solid foods. Open window for immune tolerance to allergens. Mobility increases. The onset of "separation anxiety" and "stranger anxiety" — normal signs of cognitive development (showing she has built attachment and memory of who's familiar).
Expected milestones (by end of 9 months)
- Sits firmly without support
- Crawls or scoots
- Pincer grasp (thumb and forefinger)
- Babbles with double syllables ("mama", "papa", "baba")
- Wary of strangers
- Searches for hidden objects (object permanence consolidated)
Introducing solids
The WHO and AAP recommend introducing solid foods starting at 6 months (not before), continuing breastfeedingWHO 2023. The baby must meet readiness criteria: sit with little or no support, hold head firmly, show interest in food, and have lost the extrusion reflex.
- Allergens early, not late. The LEAP study (Learning Early About Peanut Allergy) showed that delaying introduction of peanut, egg, gluten, fish, and dairy increases allergy riskDu Toit et al. 2015. Current guidance is to introduce between 4-6 and 6-12 months.
- BLW or purées? Both approaches are valid. Baby-led weaning has benefits in food self-regulation and oral motor skill. The AAP finds no evidence of increased choking risk in BLW done correctly.
- Iron and zinc are priorities. Fetal iron stores run out by 6 months. First foods: meats, egg yolks, beans, lentils, fortified cereals.
- No salt, no sugar, no honey before 1 year. Honey is strictly forbidden before 12 months (botulism risk).
Other practices
- Crawling matters. Don't skip this stage. Crossing the midline integrates brain hemispheres. Avoid walkers — banned in Canada, discouraged by the AAP.
- Welcome separation anxiety. It's a sign of healthy attachment. Don't disappear "to avoid" the crying — say goodbye, return predictably.
- Cause-and-effect play. Banging on the piano, dropping blocks on the floor, pressing simple buttons. The start of causal reasoning.
References
- Du Toit, G. et al. (2015). Randomized trial of peanut consumption in infants at risk for peanut allergy (LEAP). New England Journal of Medicine, 372(9). doi:10.1056/NEJMoa1414850
- World Health Organization (2023). Breastfeeding: WHO recommendations. https://www.who.int/health-topics/breastfeeding
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