A swaddle or receiving blanket is the best solution to keep your newborns warms. Swaddle blankets are great are creating a tight snuggle fit around the baby. The tightness reminds the baby of it’s time in the womb because that is the environment they are most familiar with.
In the meantime, the swaddle blanket will do its job of keeping your newborn nice and warm. To check if your newborn is too hot, look at the swaddle blanket and feel if it’s wet from sweat. If it is wet, try lighter swaddle blanket like muslin fabric which are more breathable and will help cool down the newborn a little more than traditional flannel cotton blankets. Another option is to keep your room temperature closer to 72 degrees Fahrenheit.