This is the Quest you have been waiting for to allow your Sims to have babies! Yay! A couple of things that you have to remember though, after completing this quest, you will still only be able to add babies to a house where a married couple live and there is a maximum number of 4 sims per house (under normal circumstances).
To complete this Quest you have to get your game to Level 8, then it will become available as a quest after you have completed all prior Quests.
Here is a rundown of what you need to do to complete the Two and a Half Sims Quest. Please bear in mind the tasks do change from time to time as the game is updated, but this list is correct at the time of publication. Also times for some tasks in the quest will vary according to the star levels of your Items.
Be nice to a sim
Expand or create a room
Spend S450 on wallpaper and flooring
Read better farms and cradles magazine - You can find this in the pile of magazines in the living room (so you may need to purchase the mags first)
Have a double shot of coffee
Watch 'Dr. Cots' on TV
Build the Children's store
Buy a crib
Add a baby
And now your Quest is complete.
Don't forget to check out our guide to babies here:
http://www.supercheats.com/the-sims-freeplay/walkthrough/baby-guide