Amid a three-series stretch against last-place teams, the Cardinals had a 4-4 record entering Wednesday night's contest with the Padres.
Mike Matheny's team exited the night with a 4-2 loss, a struggling offense and a sub-.500 record in their past nine games against teams in the cellar.
Martinez's child will be born in Venezuela. The first baseman leads the Cardinals in batting average (.322), home runs (10) and RBIs (42).
1. Travis Jankowski, LF
2. Cory Spangenberg, 2B
3. Eric Hosmer, 1B
4. Christian Villanueva, 3B
5. Freddy Galvis, SS
6.