My brother and sister-in-law just had another baby as well, their fourth. So welcome to the world, Lillian Marie!
You have a hard road ahead, being the youngest of four. I know because I am, too. But it gets better. You will be largely neglected until all your older siblings finally leave the house, and then you will become totally spoiled, and your parents will be so tired of having dealt with unruly teenagers that you will be allowed to run wild with little or no supervision. Then when you're older and all your siblings are lame and/or married and saddled with their own children, they will envy your still carefree lifestyle. It's a pretty sweet deal.