Moving a little one from their cot to a big girl/boy bed is a major transition: for children and for parents, but there are a few things that can help make the the transition a bit easier. I think it’s important to either move the toddler a month or two before a new baby arrives, or a month or two afterwards, so that she doesn’t feel resentful about the new baby taking her cot as well as her parents’ attention. The toddler should also have some sense of ownership of the decision, such as being involved (or thinking that they’re involved!) in choosing the bed and linen. It is also worth talking to them in advance about beds and big girls/boys, letting them try naps on grown up beds, and showing them older siblings/friends’ beds. Also, using dolls or toy animals to demonstrate can be a way to explain it. Ensuring that the toddler still has the same teddy, or blanket (see my post on transitional objects) can make the new bed seem more familiar. I’ve read that some people leave the cot in the room as well as the bed and allow the child to choose. I feel that it’s better to just make the transition straight away and it is ultimately less confusing for the child.
It is bound to be frightening initially for toddlers: all they have ever known is their cot, with high sides to keep them in. It is also anxiety-provoking for parents, who worry that their child will be frightened, or fall out and hurt themselves. As with all big developmental changes in our little ones, there’s a mixture of excitement about them growing up, and some sadness that they’re taking another little step towards independence. And as always, I think it’s more of a big deal for parents. Our children seem to take it all in their stride, and they love growing up and being big kids.