The 29-year-old's mother, Paula Hart told the magazine her daughter is three months pregnant.
"Melissa is feeling great -- so far, so good," she said.
It will also be the first child for Hart's husband, Mark Wilkerson, the 28-year-old lead singer and guitarist for the hard-rock trio Course of Nature.
The couple met at a Kentucky Derby party in May 2002, and married in July 2003 in Florence, Italy in front of cameras for the ABC Family special "Tying the Knot: The Wedding of Melissa Joan Hart."
Hart's latest film "Jack Satin" is expected to hit theaters this year.