The 35-year-old -- who revealed in February that she wanted one more baby with husband Alec Baldwin -- took to Instagram on Thursday to share that she is "most likely experiencing a miscarriage."
"I always promised myself that if I were to get pregnant again, I would share the news with you guys pretty early, even if that means suffering a public loss," she wrote. "I have always been so open with you all about my family, fitness, pregnancies...and I don't want to keep this from you, just because it isn’t as positive and shiny as the rest. I think it's important to show the truth...because my job is to help people by being real and open."
"Furthermore, I have no shame or embarrassment with this experience," she added. "I want to be a part of the effort to normalize miscarriage and remove the stigma from it. There is so much secrecy during the first trimester. This works for some, but I personally find it to be exhausting. I'm nauseous, tired, my body is changing. And I have to pretend that everything is just fine -- and it truly isn't. I don't want to have to pretend anymore. I hope you understand."
Hilaria continued on, explaining that the embryo has a heartbeat, but it isn't strong. "The baby isn’t growing very much. So we wait --and this is hard," she admitted. "So much uncertainty...but the chances are very, very small that this is a viable pregnancy. I have complete confidence that my family and I will get through this, even if the journey is difficult."
"I am so blessed with my amazing doctor, my dear friends, and my loving family," added Hilaria, who shares four children -- daughter Carmen, 5, and sons Rafael, 3, Leonardo, 2, and Romeo, 8 months -- with Alec. "My husband and my four very healthy babies help me keep it together and have the perspective of how truly beautiful life is, even when it occasionally seems ugly. The luck and gratitude I feel that I am my babies’ mommy, is wonderfully overwhelming and comforting."
To conclude her post, Hilaria asked that fans "please be kind" in the comments, as she is "feeling a bit fragile" and needs support. "I'm hoping, that by sharing this, I can contribute to raising awareness about this sensitive topic," she explained.
Hilaria's post comes just one day after Alec appeared on The Tonight Show Starring Jimmy Fallon, where he was asked if he had any interest in having more kids with Hilaria.
"We would have another one," he replied. "We always say when the baby comes, you look at the baby and you're like, 'How can we -- What are we gonna do? Send it back?' You know, we always think, 'This is perfect.'"
"All of our kids are, like, magical, so we would have another one," he continued, joking that "after that, my wife's gonna have to have her second husband, her next marriage."
ET caught up with Hilaria earlier this week, where she opened up about the unglamorous side of motherhood. Hear her thoughts in the video below.