In the preview, Leah is shown telling her twins, Ali and Aleeah, that they'll be getting a little brother or sister. Unfortunately, the celebration came to a sudden halt when the young mom discovered she'd lost the baby.
Jeremy told OK! magazine in January that losing their child was "a devastating experience."
But there's always light at the end of the tunnel. Just this week, Leah announced that she's got another bun in the oven, and that she's due sometime this winter.
"We feel incredibly blessed and look forward to this next chapter in our lives,” the 20-year-old told Us Magazine.
Teen Mom 2 Season 3 premiere on Monday, Nov. 12 at 10 p.m. ET on MTV. Will you watch?