TheFashion Star mentor has learned she's expecting a son with fiance Eric Johnson, RadarOnline reported.
"It's Jessica's dream come true, she prayed she was having a boy," a source close to the Simpson family told RadarOnline, adding that the couple is already discussing potential baby names.
"What with everything going on in her personal life, and her problems with her father, this has given her something to smile about. She found out this week after a check-up at the doctor, who asked her if she wanted to know the sex of the baby. Jessica immediately said yes and when the doctor told her it was a boy she screamed with joy."
Simpson and Johnson have an eight-month-old daughter together named Maxwell Drew, who was born on May 1.
Simpson made the announcement she's expecting Johnson's second child in a Christmas Day tweet in which she posted a holiday photo of Maxwell sitting in the sand with "BIG SIS" written in the sand in front of her.
Simpson, who is set to star in an NBC pilot presentation for a potential television sitcom, has recently admitted the new pregnancy wasn't planned, as she was "extremely shocked" when she first found out she was expecting again.