This is a wise question, Tanya, as moving is a traumatic experience for children of any age. And, since your 18-month-old child would not be able to understand any explanation that you might give, preparation for the move can be difficult.
Do as much as you can to communicate what is going on. If the move is within the same city, be sure to take your baby to see the new place, inside and out. “Here is where we’ll park the car. Here is where we’re going to put your slide. And here’s our new kitchen; that’s where we’ll cook our food and eat. And here’s your room; we’ll put your bed right there.”
If you can’t have an actual visit, do as much as you can with pictures. “Here’s our old house (or apartment), and here’s our new one. Put your finger on the picture of the old house. Show me the new house.” Check out a book about moving. They’re mostly going to be for older children, but they will show pictures of the vans. And give him one of the moving boxes and let him put his favorite toys in it.
And if you’re going to move, you haven’t got time for much more than this!
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.