The Friends With Kids actress is apparently concerned about starting a family before she becomes too old and wants to become a mother in the near future.
"She's worried that she's getting too old; she either has to start trying immediately or adopt," a source told In Touch Weekly.
The insider went on to say that Wiig has not yet discussed the possibility of parenthood with boyfriend and Strokes drummer Fabrizio Moretti, adding: "She hasn't broached the subject with Fab yet. She wants her own kids badly, but adoption is an option."
Wiig recently teamed up with the writers of The Descendants to direct a forthcoming action comedy film.
She will also appear in The Secret Life of Walter Mitty, also starring Ben Stiller.