Short answer: Tell a toddler about the new baby fairly late, link the timing to something they understand, and be honest that newborns mostly cry and sleep. Avoid making other big changes (new bed, nursery, potty training) right around the birth. Protect one-to-one time with your eldest, let them help in small real ways, and expect some going backwards after the baby arrives — it's common and usually passes. Children react in very different ways, and many adjust better than parents fear.
You're happy. And at the same time you look at your eldest and think: I'm about to take something away from you. That feeling is common, and it passes. It helps to know what you can do — and what to avoid.
How children react
A review of 30 studies on firstborns' adjustment to a new sibling found that children vary hugely. Some had a time of disruption, some made developmental leaps, and some showed little change at all. The most consistent finding was a dip in affection and responsiveness towards their mother for a while; changes in sleep, anxiety, aggression or “regression” were more mixed. In other words: there's no single script, and a hard patch doesn't predict a hard future.
When to tell them
Later than you might think. Nine months is an eternity to a toddler. Many parents tell a young child when the bump becomes obvious, or a few months before the birth. Link it to something concrete: “when it's summer” or “after your birthday”, rather than a date.
What tends to backfire
- Linking big changes to the baby. Moving out of the cot, starting nursery, giving up the dummy: do them well before or a few months after the birth, so your eldest doesn't lose everything “because of” the baby.
- “You're the big sister now!” as a reward. They didn't ask for it, and “big” often sounds like “more jobs”.
- Promising it'll be fun. For months, a newborn is loud and boring to a toddler. Be honest: “At first the baby will cry a lot and sleep a lot. Playing comes later.”
The less you sell the baby as a party, the less disappointment there is to deal with.
What helps
Involve them at their level
Coming to a scan if allowed, choosing between two names you both like, packing a little box for the baby together.
Read books about new siblings
Including ones where the main character is cross. Especially those — they give words to feelings your toddler can't yet name.
Protect your bond
Create a small routine that belongs only to the two of you, and keep it going after the birth. That way something stays the same when everything else changes.
Plan the first weeks
Arrange for someone familiar to focus on your eldest — not just practically, but with attention.
The first meeting
Let your eldest come in when the baby is not in your arms. Put the baby in the cot for a moment so your arms are free for your first child. A small present “from the baby” works for some families; others skip it.
Expect some going backwards
Wetting again, baby talk, wanting a bottle, night waking, clinginess or anger are all common. It isn't really going backwards; it's a way of asking, “Am I still important?” Go with it rather than against it: give them some time to be little. It usually settles within weeks.
Safety
Never leave a baby alone with a toddler, however loving they seem. Toddlers can hug too hard, give the baby things to eat, or try to pick them up.
And your guilt
In the early months it can feel like your eldest is losing out. There is, simply, less of you to go round for a while. What they're gaining isn't visible yet: someone who may walk alongside them for the rest of their life.
When to get advice
Talk to your health visitor or GP if your eldest's distress is intense or lasts for months, if they seem very withdrawn or anxious, or if aggression towards the baby is a safety concern.
Related reading
For families with more than one child: Siblings: From Rivals to Allies (PDF, English) covers jealousy, conflict and truly seeing each child.
Sources
- Volling BL. Family transitions following the birth of a sibling: an empirical review of changes in the firstborn's adjustment. Psychol Bull. 2012;138(3):497–528. doi:10.1037/a0026921.
- NHS — Dealing with child behaviour problems (life changes such as a new baby).
Written by the Bloom Guides editorial team. Last updated: 20 October 2026. General information only.