Robin Thicke's pregnant fiancee April Love Geary has fired back at body-shaming critics after sharing a nude photo of her growing belly online.

The model, who is expecting her third child with the Blurred Lines singer, posted the sultry mirror selfie on Instagram on Wednesday, after posing naked in her bathroom, with her hair draped over her breasts and one hand cradling her bulging bump, obscuring her genitals from view.

"Baby mama," she wrote in the caption.

Many of her followers heaped praise on April for her beauty and body confidence, but there were some negative reactions to the mother-to-be baring all online - and she was quick to put her haters in their place.

After one troll remarked, "Girl !! What are you doing?", April responded, "Mowing the lawn? What does it look like I'm doing???"

"@aprillovegeary it looks like you're doing to (sic) much !!!," the Instagram user replied, adding: "Your body is for your husband to see not the (world)".

Brushing off the remark, April shot back, "I don't have a husband????? Also, no man owns MY body."

And when another follower insisted she would "never" share a naked photo publicly and suggested April should keep her curves under wraps because she has "children and a baby daddy", the mother-to-be coolly fired back, "good for you".

April and Robin, who began dating in 2015, are already parents to daughters Mia, two, and Lola, 21 months, while the crooner also shares 10-year-old son Julian with his ex-wife, actress Paula Patton.