IKEA and Swedish design agency Åkestam Holst have created an advert that acts as a pregnancy test, revealing a special offer when it detects a positive result in a woman's urine.

At first glance, the design – which featured in a Swedish women's magazine – appears much like an ordinary IKEA advert promoting the brand's Sundvick baby crib.

But further down the page, women are instructed to apply a sample of urine on a marked area. If they are pregnant, their urine will cause the advert to change, to show a special discount offer on the crib.

While it looks as though the advert is offering a discount to pregnant women, it is actually intended to advertise IKEA's membership club IKEA Family.

"The whole ad is a pregnancy test that actually interacts with your potential pregnancy," said Åkestam Holst, an ad agency based in Stockholm.

"Instead of a simple line indicating a positive result, IKEA presents you with a better price on a new baby crib if you're pregnant. All in real time, right there in the ad."

To create the advert's interactive function, IKEA and Åkestam Holst partnered with materials research company Mercene Labs.

The starting point was a strip found inside pregnancy tests, which reacts to the pregnancy hormone human chorionic gonadotropin (hCG) and causes a change in colour.

Across a period of four months, the team worked to scale up this standardised method so that it would work for an A4-sized printed advert.

"Mercene Labs used their experience in development of surface active materials for microfluidics and medical diagnostics," explained the studio. "Careful selection of materials, together with a controlled capillary flow have been crucial for the success of this project."

This isn't the first time IKEA has applied a tongue-in-cheek approach to its advertising campaigns.

In 2017, the company released a spot-the-difference guide after its iconic blue tote bag was copied by fashion house Balenciaga, and also created a spoof instruction manual that shows how to make your own Game of Thrones cape from one of its rugs.

The Swedish flat-pack furniture giant, founded in 1926, topped Dezeen Hot List in 2017 for its vast range of initiatives over the past year.

These include the introduction of snap-together furnishings, which do away with fiddly Allen keys, and a collection of no-waste products.