The model gave her husband a second child.
The couple announced the birth on Twitter this morning, with Chrissy posting "Somebody's herrrrrrre!" with happy face and baby bottle emojis.
Teigen kept her fans updated on Twitter about the IVF process and posted past year that she was down their last embryo, the report said.
Just last week, Chrissy had been telling fans that she was so OVER being pregnant. "Wanna hold my boy let's do thisssssss (sic)", she tweeted earlier this month.
The baby's birth comes days after Teigen took to Twitter to vent that she was exhausted of being pregnant. 'It's hard though, because she's definitely jealous of John and I. She's so protective of John, and when we kiss, she like, looks [up] from no matter where she is'.
They explained: 'Luna's gonna be an issue. She's used to being the centre of everything right now so we'll see how she adjusts to sharing the spotlight'. The couple married in Como, Italy on September 14, 2013.