The surprise baby news comes just one week after the couple confirmed they had called off their engagement.
The actress had originally informed her fans she was engaged to Paul Michael – who she met in rehab late last year – on Valentine’s Day. However on march 8 Paul confirmed they had gone their separate ways.
'We did... I love her though, she's my best friend,” he told In Touch of the split.
Amanda originally shared news of her engagement on Valentine’s Day this year, uploading a snap of her huge diamond ring. "Engaged to [the] love of my life," she captioned the post.
The Hairspray star is still under her parents’ conservatorship, so would not have been able to get legally married without approval from a judge.
A source told The Blast at the time that Bynes' family were aware of the engagement but no one had signed off on the marriage.
Amanda’s history with substance abuse and brushes with the law are well documented.
The Easy A actress was charged with driving under the influence in 2012, and in 2013 she was caught smoking marijuana in the lobby of her New York apartment, she then threw her bong out the 36th-floor window when police were called.
That same year she started a fire in a stranger's driveway and was placed under psychiatric hold for 72 hours.
A year later she made - then took back - sexual abuse allegations against her father, Rick. She explained her decision to make the accusation: “The microchip in my brain made me say those things but he's the one that ordered them to microchip me.”