The Nationals placed Garcia on the paternity list Friday, Andrew Golden of The Washington Post reports.
Garcia (1-2) picked up the win in Sunday's extra-innings victory over the Brewers, allowing one hit and two walks over two scoreless innings. He struck out one.
The Nationals activated Garcia ahead of Wednesday's game against the Brewers, Bobby Blanco of MASNSports.com reports.
Garcia was claimed off waivers by the Nationals on Tuesday.
Garcia has made three appearances for Triple-A Jacksonville since being optioned to the affiliate July 18, striking out seven over 3.2 innings while allowing two runs (one earned) on three hits and one walk.