One of life's biggest transitions is going from being without a child to having one. Having a child changes many things:
1) No longer is there just "you" to plan for. You have another life to care for and cherish.
2) Having a child often makes you more aware of your mortality.
3) Having a child changes some of your perspectives, outlook and choices
4) No matter how old your child becomes, they are still your child in your heart.
Enjoy parenthood. Realize and accept there will be many challenges and changes in your life.