Jennifer Aniston is preparing to become a single mother.

The 'Marley and Me' actress, who split from musician John Mayer earlier this month, is so desperate to have children she is considering adopting or using donated sperm.

A source said: "In a perfect world, she'd get pregnant naturally. But if 'Mr. Right' doesn't show up, she's willing to adopt or try in vitro fertilisation using donated sperm. She is working out how she wants to proceed. But one thing is definite — she wants a baby, and she wants one soon. She is willing to become a single mother."

Although Aniston (40) is disappointed things didn't work out with 31-year-old Mayer, she accepts it was too soon for him to become a father.

The source added to Life and Style Weekly magazine: "She was hoping to have a baby with him. But I think deep down she knew he probably felt he wasn't ready to settle down and start a family. She has decided to go ahead and have a baby on her own. She knows the one luxury she doesn't have right now is time."

Earlier this week, it was reported Aniston has vowed never to marry again — because no man will ever compare to her ex-husband Brad Pitt.

Following failed romances with Mayer, Vince Vaughn and Paul Sculfor, Aniston is reportedly feeling disillusioned about dating and doesn't want to risk having her heart broken any more.