Start early, and keep it ordinary

The HSE's advice is to "talk to children early and often about the new baby" rather than making a single announcement. The AAP suggests attaching it to real events: "you can mention that a new baby will be in the family when you start buying nursery furniture or baby clothes."

For a child of one or two, the AAP is realistic about comprehension: "they may not understand why you are excited, but your attitude will rub off on them, and they will feel excited too." It suggests reading children's books about newborns and siblings, which "can help them become familiar with words such as sister, brother and new baby."

The HSE adds several things that are easy to do and disproportionately effective: "share the story of when they were born and what they were like as a baby", let them help by chatting about potential names, and "bring them to visit friends who have babies" so a real newborn is not the first one they meet.

For a two-to-four-year-old, the AAP recommends honesty over salesmanship: "be honest. Explain that the baby will be cute but will also cry and take a lot of your time." A toddler who has been promised a playmate is going to be badly disappointed by an actual newborn.

Move the big changes early

This is the most practical piece of advice in the whole subject, and both bodies give it.

The AAP: "if you can, finish toilet training or switching from a crib to a bed before the baby arrives. If that is not possible, put it off until after the baby is settled at home." The HSE says the same: "if you need to make changes in your routine with an older child, do this before the baby arrives. For example, moving into their own bed."

The reasoning is simple. A toddler evicted from their cot the week a baby arrives draws an obvious and correct conclusion about cause and effect. The HSE's toilet training guidance makes the same point from the other direction: "it is not a good idea to start toilet training if you are about to move home or have a new baby."

If it is too late to move a change early, move it late. Weeks after the baby is home is better than days before.

Tell them what will happen

The HSE recommends telling your child specifically "what will happen when you go in to have your baby" and "who will look after them and where". The AAP's version: "explain that you will be back with the new baby in a few days. You can tell your child that you and the new baby will need to stay in the hospital until the doctor says it's OK to go home."

Vagueness is worse than detail here. A toddler who knows that Granny is collecting them from nursery and that you will be back after two sleeps has something to hold on to. A toddler who is told only that Mummy is going away does not.

Expect jealousy, and expect regression

The HSE is direct: "it's also normal for children to feel jealous of a new brother or sister. Some children go back to baby behaviour. A toilet-trained child may wet themselves again or have tantrums."

The AAP explains what the regression is for: "expect your child to regress a little. For example, your toilet-trained child might suddenly start having 'accidents,' or they might want to take a bottle. This is normal and is your older child's way of making sure they still have your love and attention." Its wider guidance on toilet training regression lists "the mother's pregnancy or the birth of a new sibling" as one of the standard triggers, and adds that regression "can actually be a healthy way for a child to meet her emotional needs at a time when life feels overwhelming."

The AAP's response is worth quoting because it cuts against instinct: "instead of telling them to act their age, let them have the attention they need, and praise them when they act more grown-up." The HSE notes behaviour may also swing the other way — "some children might show anger, or even a preference for one parent or another at this time."

What actually helps once the baby is home

Small amounts of undivided time. The HSE: "even 10 minutes of time alone with them is good. This may help to make them feel secure and adjust to their new position in their family." Quality here means phone down, not day out.
Keep the routine. "Keep your family routine as normal as possible" and "keep up with their routine or activities." Nursery, swimming, the same bedtime.
Include them in the feeds rather than banishing them. The AAP suggests making your child "feel that they are a part of things by having them cuddle next to you when you feed the baby." The HSE adds: "talk to them when changing nappies and feeding the baby."
Invite help, do not conscript it. The AAP: "find ways to invite your child to help. You want to make sure your child feels included and not excluded. This helps build a bond between siblings, reduce jealousy and promote curiosity." The HSE's balancing instruction: "do not force them to be too involved."
Narrate the baby's interest in them. One of the HSE's best suggestions: "notice and name your older child when the baby looks in their direction or smiles at them."
Manage the visitors. "Praise your older child in front of visitors. Think about how visitors could make your older child feel included." Both bodies mention a gift — the HSE suggests having "the new baby bring the older child a gift", the AAP a special gift or a one-to-one outing.
Be explicit that you love them. The HSE: "let them know you love them and that they are an important part of the family."

Safety around the baby

The AAP's advice is to "teach them how to hold the baby" and to "praise them when they are gentle and loving toward the baby" — teaching the behaviour you want rather than only forbidding the one you do not.

Practically, a toddler and a newborn should not be left alone together, even briefly and even when the toddler is being lovely. That is not distrust; it is the same reasoning behind the NHS's advice never to leave a baby unattended on a bed or sofa. Toddlers are affectionate, strong and completely without judgement about what is safe.

When to ask for help

The HSE lists the routes plainly: for advice about coping with your child's behaviour, contact your public health nurse or your GP or practice nurse. In the UK that is your health visitor or GP.

Worth a conversation rather than a wait:

Regression that persists for many weeks, or wetting that comes with pain, blood or foul-smelling urine — the AAP advises a child be examined "to be sure the cause is not physical", since constipation and urinary infection can both present this way.
Aggression towards the baby that is not settling with supervision and redirection.
A marked and sustained change in your toddler: withdrawn, not eating, sleeping badly.
Your own mood. The HSE's guidance for parents is that GPs and public health nurses can support you when you are under pressure, and the postnatal period is when that matters most.

Most of this settles. The HSE's framing is the right one to hold: "when a newborn baby joins the family it takes time and patience for other children to adapt to the change." Adaptation is the process, not a sign that something has gone wrong.

Sibling Arrival: Preparing a Toddler