Roberts got word Thursday morning that Kim was going into labor, and he immediately called and sent a text message to manager A.J. Hinch before catching a flight to Phoenix.
Roberts will rejoin the D-backs to face the Nationals this weekend in Washington, provided all goes well.
With the trade of second baseman Felipe Lopez to Milwaukee last month, Roberts has gotten regular playing time at second, and the 28-year-old has made the most of it.
In the first two games of the series against the Pirates, Roberts hit three homers.
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.