"She's young to be a mother of three, but she really loves being a mom," the pal said.
"Jeremy and I are excited to be adding a new addition to our family," the 20-year-old told Us Weekly. "Being a teen mom was difficult, but I'm older and in a different place now - married to Jeremy and excited for our family to grow."
Leah and her husband suffered a miscarriage in January, which Calvert called "a devastating experience."
Teen Mom 2 returns to MTV November 12.
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