The expectant mother revealed the news to her Instagram followers with a photo of her and Alec sharing a kiss. "Ireland, Carmen, Rafael, Alec, and I are excited to share with you that we are going to have another addition to our family. A little boy coming this fall #366daysoflivingclearly #HilariaLCM," she wrote on Wednesday.
Her thousands of fans were quick to congratulate the pair. "Congratulations to your whole family. You look amazing," one fan wrote. "Yeah!!!! 💙 So happy for you and Alec," another added.
Hilaria and Alec are expecting their third child together
The doting mother often shares sweet snaps and videos of her kids on social media. "Celebrating #internationalwomensday with a smoothie and a kiss! Happy day, ladies!," she wrote alongside a photo of her and Carmen this week.
The happy couple welcomed Raphael Thomas Baldwin on 16 June, shortly before their third wedding anniversary.
Hilaria gives daughter Carmen a kiss
Their love story began in 2011 when Alec spotted Hilaria at a restaurant and gave her his business card with his personal mobile phone number jotted down on the back.
After a year-long courtship the actor proposed and the wedding took place at St Patrick's Old Cathedral in New York, with celebrity guests including Tina Fey, Woody Allen and his brothers Stephen and Billy Baldwin. Showing her approval, the groom's daughter Ireland was the maid of honour.
Alec told HELLO! magazine at the time: "Marriage was made for you to make a commitment to someone who is worth it, and I met someone who is worth it."