I agree with the other comments--tell us more!!!
My specific comments:
First paragraph: (It was 4 hours...) You're starting out by giving away the ending. There's nothing wrong with that, but it makes it a little more difficult to transition smoothly into the rest of the story, and it kind of builds up my expectations for how you will end your story.
Second paragraph: You're starting the actual narrative with transition! I know you had a quick labor, but surely SOMETHING was worth mentioning before transition. When did you think you were in labor? What had you been doing? How did you labor? Did you breathe through contractions? Sit in the tub? Use a birthing ball? When did your water break? Tell us everything! Why did you think your daughter was home, and how did you find out she wasn't? What were you thinking and feeling? Also, you may want to say something about the kids' ages within the story when you first introduce them. I skipped over the title, so in my first reading they seemed much younger and it really changes the story!
Third paragraph: When dd came in, do you mean to the house or to the room? What did you do during the time between when ds1 left and dd showed up? Tell us the good and the ugly. Were you afraid? Did you ever have any second thoughts about your UC during the birth? How did you push? What position were you in? How long did it take for the head to come out? What did you think when you first saw your son? Did you ask your dd to wait outside until you called her into the room? How did your daughter react to everything?
Fourth paragraph: We get some insight into your thoughts here--this is what I'd like to read through the whole story.
Fifth paragraph: I agree with the previous poster--we need more explanation about ds1's involvement with naming the baby.
Last paragraph: I like the hair color part, but it doesn't feel like an ending to me. Since I knew from the beginning that everything went quick and smoothly, I kind of expect something big here--maybe your emotional response to the birth and your new son.
Congratulations on your UC! You have a great story and I can't wait to read the fleshed out version.