When a female teenage Sim is having a baby, she may have a miscarriage or it can be caused by the player selecting the option on the pie menu for the biological clock. The PlumbBob will glow red, and the Sim will start grasping for her stomach. A thought bubble with a pacifier and a question mark will come up. The Sim will then be in her normal clothes, and start crying.
Also, when a teenager has only 8 days left of their teen lives and become pregnant, they are exempt from schooling and can work full time.