"Ali and Hayes are thrilled to be expecting their first child," her rep tells PEOPLE exclusively. The baby is due this winter.
Having a family has long been in the cards for the actress, 34, who wed MacArthur in Kennebunkport, Maine last August.
"I told my boyfriend after three weeks that I wanted to marry him and that we could do it tomorrow," Larter told Cosmopolitan in 2007. "I look forward to that time when I'm home with babies."
Reporting by JENNIFER GARCIA