I remember watching my friend's toddler struggle with adjusting to the new baby, and that was the moment I decided to try things differently if and when I did have kids of my own.
And then d-day arrived, I was pregnant with my second child. The first person we spoke to was our 3 year old daughter, and she looked at us weird like "what are you on about?".
I knew I had just a bit under 9 months to get her used to the idea of loving someone smaller than herself and sharing her mum and dad. I started involving her in all my doctor appointments and ultra sounds (the look of amazement on her face said I was doing it right).
Talking to her about the baby was really important and making sure she knew that she was still my little girl. Gradually her excitement grew as did my belly, she loved placing her hands and feeling the baby kick. When family or friends would come over, she'd be all excited to let them know all about the baby. Somehow I felt reassured that things were going well with our little girl.
Finally it was time to introduce her to her baby brother, she had the biggest smile on her face and asked if she could take him out to play.
Since then they have been the best of friends, and of course like all siblings do, they fight like cat and dog.
So all I would say to parents is don't be afraid to involve your toddler, they are very smart little beings. Your new born doesn't actually need you for the first few months other than to be fed, burped and changed, so use this time to get closer to your toddler and show him/her that things haven't changed. Give him/her those special cuddles more often. All they need is that little reassurance that you're still there for them.