Gigi Hadid has been using fashion ''optical illusions'' to hide her baby bump.

The 25-year-old model is currently expecting her first child with her boyfriend Zayn Malik, and although she should be displaying a burgeoning baby bump, she's managed to conceal it from view by using ''baggy'' clothes.

During an Instagram Live with chef and welfare advocate, Sophia Roe, Gigi was asked about her bump by a fan who commented: ''How do you not have a tummy?? I'm 4 months into my pregnancy and my tummy is huge you look great tho! (sic)''

And the beauty responded: ''This angle and the really baggy jumpsuit make for an optical illusion. From the side it's a different story! haha -- wishing u the best! x (sic)''

Gigi has been keeping her pregnancy private since she announced it back in April, but previously revealed she already knew she was ''a few months'' pregnant when she was walking the runways during Fashion Month in February.

Speaking in May, she said: ''People think I do fillers on my face, and that's why my face is round - I've had this since I was born. Especially Fashion Month, when I was already, like, a few months preggo, you know.''

The beauty is reportedly due to give birth in September, and she previously said she is ''very excited'' to become a mother.

She said: ''Obviously, we wished we could have announced it on our own terms but we're very excited and happy and grateful for everyone's well wishes and support.

''Especially during this time, it's a nice silver lining to be able to be home and be together and really experience it day by day.''