In their first week kittens arrive with closed eyes, folded ears, and no ability to shiver or regulate body temperature. Their mother's body and the nest you provide are their entire heating system, and chilling is one of the fastest routes to a fading newborn, so warmth deserves the same seriousness as feeding.
Build a nest that holds warmth in
Choose a box or crate with sides high enough to block draughts and contain crawlers, placed in the quietest, warmest room away from doors and windows. Line it with several layers of fleece or towels you can change the moment they soil, since a clean dry nest insulates and a damp one steals heat. Keep spare bedding warming nearby so changes do not mean a cold swap. The nest should be large enough for the mother to stretch out and for kittens to shift position, but small enough that they naturally pile together and share body heat rather than scattering and cooling alone.
Heat one end, and always leave an escape from it
Place a covered heat pad or warm water bottle beneath the bedding at one end only, set low and checked often, so the gradient does the regulating the kittens cannot: they crawl toward heat when cold and away when warm. Covered sources matter because newborns cannot move away from a pad that is directly against them in the first days and can overheat or burn without ever making a sound. Aim for a nest temperature in the low thirties Celsius at kitten level during the first days, easing slightly as the week progresses, and judge by behaviour too — kittens spread out and panting are too hot, while a tight, constantly crying pile that feels cool to touch is too cold.
Keep the mother, handling, and room calm
If the mother is present, her body is the kittens' main heat source and the nest simply supports her: feed her beside the nest, keep visitors and other pets away, and let her leave briefly without the kittens being carried off for show. Handle newborns briefly and with warm hands, mainly for weighing and health checks, then return them to the pile. Keep the room itself steady and warm so trips out of the nest for weighing do not become chilling events, and wash hands before handling to protect kittens whose immunity is still borrowed from their mother.
Cold, quiet, or scattered kittens need fast help
A kitten found cold and limp away from the pile should be warmed gradually against your body or with gentle external warmth — never fed while cold, because a chilled kitten cannot digest safely — and a veterinarian or experienced rescue should be contacted the same day. Repeated crying, failure to settle and nurse, or a mother who will not stay with the litter also warrant prompt advice. Warmth failures move faster than almost any other newborn problem, so checks through the night are part of the setup, not an extra. Assigning those overnight nest and warmth checks in KinsLe Care Teams, with each completed round timestamped, protects these first-week kittens when their carers are working in shifts.