Neither of the celebrities have publicly announced the pregnancy.
Hadid, who turned 25 last week on April 23, posted photos on her Instagram account, noting that she celebrated with her "quarantine family," which included Malik. Hadid's sister, model Bella Hadid, was also in the photos.
"I am grateful and lucky that my family and friends - near and far- are healthy and safe, and although I missed loved ones I wish I could have celebrated with, know that these times will make us even more grateful for togetherness to be had in the future," Gigi Hadid wrote on Instagram.
Malik and Gigi Hadid have dated on and off for years.
The pair first sparked dating rumors at the end of 2015 when Malik posted a picture of the two on social media. In January 2016, Gigi Hadid appeared as the love interest in Malik’s music video for the song “Pillow Talk." They attended the Met Gala together in June 2016 as well as London Fashion Week and Paris Fashion Week that same year, solidifying beliefs that the two were an official couple. Multiple public breakups and makeups followed.
More recently, Gigi Hadid posted a photo of Malik on her second Instagram account, claiming him as her valentine.
See a full timeline of the relationship here.