I haven’t personally had this experience yet, but I hear a lot of horror stories about the effect of a new sibling on a first born. Jealousy that turns into tantrums, fits, and the need to wear diapers again or drink milk from a bottle – just like the new baby. So, to minimize the effect of this, parents need to start preparing their oldest child for the new sibling, even before it arrives.

Here’s an article about possible methods that you can use – good luck!