PARIS—Spring summer fashion is about the race—often in vain—to get a flat tummy.

But that was not the case on the Paris fashion week catwalk on Tuesday, where two pregnant models walked the runways.

The French designer Marine Serre sent her mum-to-be out cradling her tummy in the drizzle at her outdoor show, while the Chinese brand Dawei had another heavily pregnant model in a vertically striped sweater dress to accentuate her bump.

Not without risks

While Serre’s choice was also to add a touch of hope to

her apocalyptic-themed show “Black Tide,” which warned of the environmental catastrophe, pregnant models are becoming something of a thing these days.

Though the trend is not without its risks.

While model Lily Aldridge batted away the worries about walking at New York fashion week last year, Slick Woods will never forget doing Rihanna’s Savage X Fenty lingerie fashion show in the city last September.

She began to go into labor just before the lights went up but she soldiered on.

The 22-year-old model was already 2 centimeters dilated when she tottered offstage.

“My last memory before going into the hospital is of Rihanna spanking me with a whip,” she later wrote in an article for Vogue.

Such was the initial rush, that the American songwriter Erykah Badu had to act as her doula over FaceTime.

But in the end her son Saphir was born after an 18-hour labor.

Woods’ due date was two days after the show.