Once a male and female pig have been paired in the Pig Plaza, a baby piglet will be born after a certain period of time. Pigs can only be paired once.
Pigs which have already been paired will have a tick indicating that they have been paired, and they can be put on the truck to be shipped from the Pig Pen.
Choose a male pig to pair with your female pig (the female pig must be your own pig). If you have male pigs in the Pig Plaza, drag the one you want to pair over to the female pig. If you don't have a male pig, tap the female pig to rent another owner's male pig. (Renting will cost you points).
After a certain period of time has passed, male pigs will return to the male area and you will be able to ship them. Female pigs will remain inside the middle area until a baby piglet is born. A baby piglet will be born after a certain period of time, and it will automatically be moved to the Pig Pen if there is space. If not, they will move to the waiting list until there is space in the pen.