Margaret, played by NiCole Robinson, is showing a pregnant belly. She was pregnant with her first child, Shirley.
The episode's place in the fictional chronology of the series coincides with its original air date in real time, January 19, 2005. The title refers to the Bartlett administration's having exactly one year left from the day that the episode is taking place. That day would be January 19, given that January 20 of the following year would be Inauguration Day for the next president.
The plotline for "Annabeth and the First Lady" is that the first lady will attend a Martinsville NASCAR race. This occurs the day after the State of the Union in January. There is no NASCAR race at all in January and the only one the president/first lady attends is Daytona, the weekend in the middle of February.