The baby cries and your dog starts barking beside the cot. You cannot tell from barking alone whether they are worried, excited, or trying to get away from the sound. Move the dog to a comfortable area behind a secure gate or closed door before attending to the baby. Do not ask the dog to inspect or comfort the baby during the crying. Never leave a baby and dog together without an adult actively supervising, even if the dog has always been gentle.
If the dog stiffens, growls, rushes toward the baby, or cannot settle with space, seek veterinary and qualified, reward-based behavior help promptly. A health change in the dog can also affect tolerance of noise. Make a plan that gives the dog a place to rest and the adult a way to care for the baby without managing both in one small space.
Build a calmer routine
At quiet times, reward your dog for settling in their own area while you move around with baby equipment. If they remain comfortable, a very low-volume recording of a baby crying may be used in short sessions, paired with a reward and stopped before barking starts. Do not play loud recordings beside the dog or use a real distressed baby as a training prop. Keep the gate and adult supervision in place as the baby grows and begins to move.
The first success is a household where a crying baby can be helped and the dog can rest safely elsewhere. Close contact is not required. For more on setting up safe spaces as baby routines change, see the dog-and-new-baby guide, keep adult supervision and barriers in place
Sources: Dogs Trust: How to prepare your dog for a new baby. Dogs Trust: Dogs and children - living happily together.