Teigen, who is married to singer John Legend, was updating fans via her Instagram stories on Thursday when she let the gender of her baby-to-be slip.
While talking about complications with her placenta she said, “It’s so weird because the baby’s really really healthy. He’s big.”
She quickly realized her mistake but laughed it off, “He’s probably, oops! That was stupid.”
Teigen and Legend already have a 4-year-old daughter and 2-year-old son.
She previously went through IVF for her two children but explained that this third pregnancy happened naturally and unexpectedly.