Why has my child regressed since the new baby arrived?

Regression after a sibling arrives is extremely common and usually temporary. A child who was toilet trained starts having accidents; one who slept through wakes repeatedly; speech becomes babyish; a long-abandoned dummy or bottle is suddenly demanded.

The logic from the child's side is coherent. They have observed that a very small person who cannot walk, talk or use a toilet receives constant attention, physical closeness and immediate response to every sound they make. Behaving that way is a reasonable hypothesis about how to get the same. It is not manipulation in any calculated sense — it is a young child acting on an obvious pattern.

There is also a genuine stress response. A new sibling is among the largest upheavals a small child experiences: routines change, a parent may have been away, attention is divided permanently, and nobody consulted them. Under stress, recently acquired skills are the first to go, because they are the least automatic. This is normal across development, not specific to siblings.

What tends to help:

Do not remove the regressed privilege as a punishment. Escalating the fight over a bottle rarely wins it and confirms that babyhood is worth fighting for.

Give protected, predictable one-to-one time, even ten minutes, named as such. Reliability matters more than duration.

Name the feeling rather than the behaviour. "It's hard when the baby needs me so much" lands better than "you're a big girl now."

Give them a real role — fetching a nappy, choosing the babygro — so being older comes with status rather than only with losses.

Expect weeks, not days. Most regression resolves within a few weeks to a couple of months. If it persists beyond that, worsens, or includes marked withdrawal or aggression, mention it to a health visitor or GP.