Maci, Amber, Farrah and Catelynn have pulled back the curtain on their respective "Teen Mom OG" journeys -- and when the long-running series returns, the four young mothers will be encountering brand-new life developments like never before. A brief spoiler: Viewers haven't seen anything quite like these highs and lows...

In the trailer above for the upcoming installment -- which will kick off MTV's new slate of programming in 2016 on January 4 -- the quartet of moms will laugh and cry as they navigate unknown milestones and battles. From Catelynn and Tyler saying "I do" to looming questions for Amber and Gary about Leah's custody, the girls will be forced to confront new realities and changes.

But that's not all: Maci declares her readiness to be Taylor's wife even though they are not engaged, while Farrah is having trouble seeing eye-to-eye with her loved ones. And just wait until you see the final moments of the teaser clip (just one word: wow).

Check out the jaw-dropping trailer, share your thoughts on the upcoming season in the comments and be sure to catch the premiere of "Teen Mom OG" on Monday, January 4 at 10/9c!