Is co-sleeping safe with a 4-12 month old baby?

What the evidence says

Health Canada, the Public Health Agency of Canada and the Canadian Paediatric Society advise against bed-sharing at any age, recommending babies sleep on their own firm, flat surface in the parents' room for at least the first 6 months. That said, they acknowledge many families do bring babies into bed, often for breastfeeding, and focus on reducing risk if this happens. The science shows the danger of bed-sharing is highest under 4 months of age, where studies report several-fold increases in sudden infant death risk, especially with smoking, alcohol, drugs, prematurity, or sofa-sharing.

After 4 months, the added SIDS-specific risk drops substantially, but a different hazard becomes more prominent: infants this age can roll and get wedged against pillows, blankets, a parent's body, or a headboard, which can cause accidental suffocation. So while an occasional, carefully managed bed-sharing session (firm mattress, no pillows/duvets, sober non-smoking adult, no other children or pets in bed, baby on back) carries lower risk at 4-12 months than in early infancy, it is not considered risk-free, and Canadian guidance still recommends a separate sleep surface as the safest option throughout the first year. If you do bring your baby into bed, the clearest way to lower risk is removing soft bedding and gaps the baby could roll into, and moving baby back to their own crib or bassinet afterward.