Gigi Hadid posted a throwback pregnancy photo while ringing in her sister Bella Hadid‘s 24th birthday.“Today I celebrate, but am always grateful for, the 24 years that I have been blessed with my baby sister @bellahadid who always has my back and brings me the yummiest treats,” the Los Angeles native, 25, captioned a Friday, October 9, Instagram slideshow. “I am so proud of your constant growth and light.