The couple - who began dating last May - announced that they were to become parents in November.
Speaking to OK magazine, former Celebrity Big Brother winner Houghton confirmed that she will have a daughter.
"I just sat there crying and Alex was completely open-mouthed," the 28-year-old said. "I can't wait to go clothes shopping for her!"
On Victoria and David Beckham's daughter Harper Seven, she joked: "Harper has got some serious competition coming along!"
Reid, who has also won Celebrity Big Brother, proposed to Houghton live on Irish television in October. He recently said of becoming a father: "We're gonna be the best [parents]. I really can't wait to be a daddy."
> Alex Reid demands apology from Joey Essex for Chantelle Houghton slam