Sarah thinks Maddox is being framed, based on the fact she knows him.
When that stops working, Sarah fakes a contraction.
In the trunk are items in plastic bags with letters on each bag.
Maddox admits he did it because Vanessa was going to throw him under the bus with her evidence about oxy.
I wrote those lines before watching the season finale, which is also reviewed below, and the pregnancy hiding gets even more creative and fun in it.
Mayko Nguyen has no children.