The 18-year-old was a picture of concern as an actress playing a Nickelodeon producer donned a prosthetic baby bump and proceeded to "give birth" during an interview with the band.
The staged prank was set up by fellow One Direction heartthrobs Louis Tomlinson and Zayn Malik, who played along as the woman moaned and screamed that her bub was on the way.
A visibly worried Harry is seen nursing the woman with her breathing exercises, while 1D's Niall Horan appears stuck to his seat in horror.
Harry is renowned for his "cougar" relationships — the teen has dated two 32-year-old UK personalities in the last year alone .
It seems spending time with ladies nearly double his age has given the pop star a mature attitude towards women.
That, or Harry's got a hidden talent for midwifery. But we doubt he'll be swapping stardom for scrubs anytime soon.
Check out the boys' reaction when all is revealed in the hilarious clip above.