A new baby is coming, and your toddler has no idea what that really means yet.
You can say the words — “you’re going to be a big brother” or “a baby sister is
coming” — and watch your toddler nod along with complete cheerfulness, entirely
unaware that their whole world is about to change.
That gap between what toddlers understand and what is actually coming is exactly
why preparation matters — and why how you prepare them matters just as much as
whether you prepare them at all.
This guide covers what developmental research actually says about preparing
toddlers for a new sibling, broken down into practical steps you can start today.
When Should You Tell Them?
Research on toddler development suggests telling a child about an incoming
sibling somewhere between the fourth and sixth month of pregnancy — not too
early, when the wait feels abstract and endless to a young child, and not too
late, when changes to your body and home become confusing without explanation.
A toddler’s sense of time is still very concrete. “The baby is coming in five
months” means almost nothing to a two or three year old. What works better:
tying the arrival to something concrete they understand. “The baby will come
after your birthday” or “when the leaves fall off the trees” gives a young
child something real to hold onto.
What to Actually Say
Keep it simple, honest, and positive — without overselling. Research on how
children process family change finds that children who are given accurate,
age-appropriate information adjust better than children who are either told
nothing or given an unrealistically rosy picture.
What works:
“A baby is growing in my tummy. When the baby is ready, they will come out
and live with us. Babies are very small and need a lot of help. You are going
to be a wonderful big brother/sister.”
What to avoid:
“The baby is going to be your best friend!” — This sets an expectation that
may not match reality, and toddlers who feel deceived by overpromising can
become more resistant to the new sibling, not less.
Prepare Them for the Practical Changes
One of the most well-supported findings in sibling adjustment research is that
toddlers who experience changes to their routine and environment before the
baby arrives — rather than at the same time — adjust significantly better than
those for whom everything changes at once.
Practical steps:
- If your toddler will be moving to a new room or a new bed, do this at least
two months before the baby arrives - If childcare arrangements are changing, start the transition early
- If a grandparent or other caregiver will be looking after your toddler during
the birth, arrange several practice visits beforehand so the arrangement
feels familiar
The goal is to separate the changes so your toddler does not experience their
whole world shifting simultaneously.
Involve Them — Genuinely
Research on sibling adjustment consistently finds that toddlers who are
meaningfully involved in preparing for the baby — not just told about it, but
given real roles — show better adjustment after the birth.
Ways to involve your toddler:
- Let them help choose one item for the baby’s room
- Read simple books about new babies together — not once, but repeatedly
- Let them feel the baby kick if they want to
- Talk about what the baby will need and what your toddler can help with
The key word is genuinely. Toddlers are perceptive. Involvement that feels
performed or forced tends to backfire. Real, age-appropriate participation —
even small — builds a sense of ownership and importance that passive
preparation does not.
Books That Help
Research on bibliotherapy — using books to help children process upcoming
changes — finds it genuinely effective for toddlers and preschoolers facing
family transitions. A few well-regarded titles:
- “There’s a House Inside My Mummy” by Giles Andreae — gentle and honest
about pregnancy and birth - “Za-Za’s Baby Brother” by Lucy Cousins — warmly addresses the mixed
feelings of a new sibling arriving - “The New Baby” by Mercer Mayer — a classic that addresses jealousy and
adjustment honestly
Read these repeatedly, not just once. Toddlers process through repetition.
After the Baby Arrives: The First Weeks
Preparation does not end at birth. Research on sibling adjustment finds the
first six weeks after a new baby’s arrival to be the most vulnerable period
for toddler regression and adjustment difficulty.
What helps most in the first weeks:
Protect one-on-one time. Even fifteen minutes of dedicated, undivided
attention daily — no baby, no phone, just you and your toddler — has been
shown to significantly reduce jealousy and regression in this period.
Let them lead the relationship. Do not force affection or interaction between
your toddler and the new baby. Let your toddler approach in their own time
and at their own pace.
Name the feelings. If your toddler seems angry, sad, or confused, name it
directly: “It’s okay to feel upset that the baby needs so much of my time
right now. I love you just as much as I always have.”
Expect regression. Toilet training setbacks, sleep disruption, and clinginess
are all normal toddler responses to a major family change. They are not signs
of failure — they are signs that your toddler is processing something big.
The Bottom Line
Your toddler will not remember the preparation you did. But the adjustment
they make — the first fragile steps toward a sibling bond that may last their
entire lives — will be shaped by it in ways that matter for years.
Start early. Keep it honest. Involve them genuinely. Protect your time
together after the birth.
The sibling relationship you are helping build right now is one of the most
important gifts your child will ever receive.
Sources
Dunn, J., & Kendrick, C. (1982). Siblings: Love, Envy and Understanding.
Harvard University Press.
Volling, B. L. (2012). Family transitions following the birth of a sibling:
An empirical review of changes in the firstborn’s adjustment. Psychological
Bulletin, 138(3), 497-528.
Kramer, L., & Ramsburg, D. (2002). Advice given to parents on welcoming a
second child: A critical review. Family Relations, 51(1), 2-14.
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