Gwen Stefani jokes: 'I'm pregnant!'

Gwen Stefani sent fans into a frenzy on April Fools' Day (01Apr16) after joking she's expecting a baby girl.

The No Doubt frontwoman decided to have a little fun on Friday by posting an image of a sonogram on Instagram, suggesting she and her boyfriend Blake Shelton are starting a family together.

"It's a girl," she captioned the photo, alongside a number of heart emojis.

Some of Gwen's Instagram followers failed to realise it was all part of a prank and congratulated her, but when others pointed out it was clearly a hoax for April Fools' Day, some began criticising the mother-of-three for her joke, claiming she was being insensitive to women struggling with infertility.

The backlash prompted the singer's fans to hit back.

"OMG (oh my God)...., really all of these offended people?" wrote one social media follower. "Geezee, get some sense of humor. If you're that bitter about #AprilFoolsjoke you need to go hide back under that cold rock you're living in. I think it was a great post @gwenstefani much respect".

Another added, "Haters gonna hate chill the f out people !!! No apology needed!!!! Do you girl!!!!"

Gwen, who shares three sons with her ex-husband Gavin Rossdale, has yet to comment on the headline-grabbing post, which was clearly a dig at recent false tabloid reports suggesting she is expecting new beau Blake's baby. The most recent claim appeared in In Touch magazine in March (16), suggesting she was having a "miracle baby at 46".

Meanwhile, Blake is brushing off the criticism his girl has attracted for her April Fools' prank after one fan asked for his opinion about the backlash.

"I ignore self appointed do gooders who b**ch and moan on social media," he responded on Twitter. "Try it. The world gets WAY better."

Gwen and Blake have been dating since October (15). The couple met while serving as coaches on U.S. talent show The Voice and struck up a romance after Gwen's shock split from her husband of 13 years, Bush rocker Gavin, in August (15).

The country singer was also newly-single following his divorce from Miranda Lambert in July (15).

Gwen recently confirmed she was in love Blake in a candid chat with VanityFair.com.

Gushing about how her new romance helped her create songs about happiness and positivity for her new solo album, This Is What the Truth Feels Like, following her shock divorce, she said, "I've never had a record that is almost all about being happy and in love."

Picking up on her declaration, contributing editor Lisa Robinson asked, "You're in love now?", to which Gwen replied, "Yeah, for sure. I don't really want to go into that relationship, and God knows what's going to happen. But I feel like I'm in an amazing songwriting place; instead of being closed off, I'm thinking about positivity and how I can do something creative. I'm just doing what I want to do. It's so incredible to be in that zone. I'm always looking for the next song, and now I don't have to be insecure or write about heartache."