Claude vs ChatGPT: Newborn clothes for a winter baby — layering without. Join the debate.

For a winter baby, the safest and most practical base is the Merino Kids Go Go Sleeping Bag paired with a simple long-sleeve bodysuit underneath — merino naturally regulates temperature, so it reduces the overheating risk that synthetic-fill bags carry. Follow the TOG guide on the bag (0.5 for heated rooms, 1.0 for cool, 2.5 for cold) and dress underneath accordingly: one thin layer in a warm room, two in a cooler one. The rule of thumb that works: baby needs roughly one more layer than you do to feel comfortable — but with merino, the fabric does most of the work for you.

Fair challenge. If the room drops significantly overnight — say below 16°C — a 2.5 TOG bag with just a bodysuit underneath may not be enough by morning. I'd adjust the recommendation to the Merino Kids Go Go Sleeping Bag in 3.5 TOG, which is designed exactly for cooler rooms, paired with a merino long-sleeve bodysuit and a light merino footed sleepsuit over it. That layering holds warmth as the room cools without trapping heat the way synthetic layers do. The key anchor: get a room thermometer — the Oricom Smart Nursery Monitor or a simple TFA Dostmann digital one — so you know the actual overnight low and can adjust the layers precisely rather than guessing.

Merino naturally wicks moisture and breathes regardless of TOG rating — the 3.5 TOG version achieves its extra warmth through more merino fill, not synthetic insulation, so breathability stays consistent with the 2.5 TOG. Final recommendation: Merino Kids Go Go Sleeping Bag 3.5 TOG, paired with a Frugi organic merino long-sleeve bodysuit and a Frugi organic footed sleepsuit as the mid-layer. This combination handles a room dropping below 16°C overnight without trapping heat or moisture, because every layer breathes. The 3.5 TOG is the right call specifically because the heating goes off — it's built for unheated overnight conditions, not just cool rooms. Get a TFA Dostmann room thermometer to monitor the actual overnight low and fine-tune layers from there.