Michael Phelps is going to be a daddy.
The 18-time Olympic gold medalist announced Wednesday on his Instagram and Twitter accounts that his fiancee Nicole Johnson is expecting their first child.
Phelps posted a photo of him and a smiling Johnson standing poolside in Arizona holding tiny black swim trunks with the initials 'MP' on it.
"We found out 8 weeks ago we are expecting," the caption says.
"Today we're over 12 weeks and it looks like we're having a boy!!!"
Phelps has said he and Johnson, both 30, would marry after next summer's Rio Olympics.
Based on Phelps' announced timing, Johnson is due to give birth next spring.
Earlier this year, Phelps completed a six-month suspension by USA Swimming after a second drunken driving arrest in 2014.