The 29-year-old YouTube personality took to Instagram to announce the news on Tuesday, on what would have been Crew's 4-month birthday. Crew was laid to rest last week, two weeks after he was found unresponsive while taking a nap at a relative's house on Christmas Day.
Leach shared the update in the caption of a maternity photo of her shot by Texas-based photographer Nicole Smith.
"I never got around to posting my maternity pictures with Crew because by the time I got them back, he had already made his VERY fast and furious entrance to the world," she wrote.
"I almost didn’t take maternity pictures because I was just so 'busy.' I’m glad I did because little did I know, he would spend more time in my belly than he did out. And while he was here he wanted to be with his Mama as much as possible. Now I know why," she added.
Leach went on to say she and her husband, Jeff, received word days ago about Crew's organs.
"We got the bittersweet call a few days ago, that his liver saved the life of a 1 year old boy, and his heart saved the life of 7 month old boy," she shared.
"He would be 4 months old today, and every fiber of my being misses him every single second of the day. But I have peace knowing that he was THE miracle that another family prayed for, and we pray that we are able to meet these precious boys one day," she wrote.
"In three short months he has touched and changed more lives than most in their lifetime and despite the pain, I’m so proud God chose me to be his Mother," she added.
Leach, a mother of three other boys and one stepdaughter, has more than 174,000 subscribers on YouTube, where she chronicles her life as a mom.
She shared heartbreaking updates about Crew as she kept vigil by his hospital bed, beginning with a post on Dec. 26 showing a photo of her cradling Crew's tiny hand.
"While at a relative’s house last night, Crew laid down for a nap and when I went to check on him, he was not breathing. We are living a nightmare, and I’m dying inside. Please pray for my baby. This can’t be real," she wrote.
She later revealed the little boy was hooked up to a ventilator, which she said was "breathing for him."
"They are working on stabilizing his body and tomorrow he will have an MRI to determine his brain function and that will determine the next step. I can’t explain to you what this feels like," she wrote, adding, "Please continue to pray. Please. I don’t think I can go on without him."
Last Wednesday, the grieving mom let followers know she and her husband had laid Crew to rest.
"We will always feel like we are missing a piece of our family, because we are," she wrote. "And until we get to Heaven, I know he’s smiling, laughing and playing at the feet of Jesus. I just wish he was here instead.”