Catelynn and Tyler Baltierra had a huge reason to celebrate on Monday night’s episode of Teen Mom OG.

The couple told Catelynn’s mother, April, and her younger siblings that they were expecting their third child together after last week’s episode showed Catelynn breaking the news to Tyler.

The two are parents to 3-year-old daughter Novalee Reign and are also the biological parents to 8-year-old Carly, whom they placed for adoption.

April was shocked when she opened Nova’s sweater and saw a pink T-shirt that read, “I’m going to be a big sister.”

“Are you serious? Really,” she asked, tearing up. Catelynn said, “I am! I swear to God! Hopefully, it’s a grand-boy,” referring to Tyler’s wish for a son.

“I’m happy with whatever it is,” April said. “Could be twins, you could get one of each!”

Catelynn called their child a “summer baby.”

The couple told Tyler’s father, Butch, separately. He told the two, “What if it’s a girl? Are you going to keep trying for a boy? Rock it out, baby.”

Last week, Catelynn surprised Tyler by having Nova walk out into the living room with a pink T-shirt that revealed the news to him. She also dropped a positive pregnancy test on the dining table in front of him.

“Oh my God,” Tyler said, seeing the test and quickly dropping his head onto his hands.

Catelynn, laughing, walked into the kitchen as Tyler asked her, “How many did you take?”

“Four,” she said. “Oh my God,” he reiterated, laughing and dropping his head again.

“Fertile Myrtle,” he said as she nodded and said, “Yeah!”

Catelynn turned to Nova, who was standing nearby, and said, “There’s a baby in mommy’s tummy.” The mother of two has not mentioned her pregnancy on her social media accounts. 

On a recent episode of Teen Mom OG, Catelynn and Tyler discussed the possibility of having another baby after he expressed his desire to expand their family.

But despite her husband’s desire for more children, Catelynn — who struggled with postpartum depression after the birth of Nova — openly expressed her fears when it comes to being pregnant.

“It’s a daily fight in my mind to not be afraid of postpartum ,” she told Tyler. “I can’t let my mind stop me from one of the most amazing things ever.”

The mother of two recently entered rehab in early January to deal with “childhood trauma.” She also entered rehab in November to battle suicidal thoughts.

Teen Mom OG airs Mondays (9 p.m. ET) on MTV.