The child will be Amber’s second as she is already mum to nine-year-old daughter, Leah with ex-boyfriend Gary Shirley.
Amber and Andrew are said to be excited about their future together," a source told E! News.
"He is with her in Indiana and the relationship is going strong. He has been filming with her."
Amber, 27 met Andrew earlier this year while she was filming Marriage Boot Camp with ex-fiancé Matt Baier.
Speaking to US Weekly about her pregnancy, Amber revealed:
When I first found out, I was a little scared. I just kind of sat down and thought about it and realized that it was a big step in my life and it was a good thing actually, and I was really happy within 30 minutes."
"After the initial shock," she continued, "it was nothing but happy thoughts and just enjoying my time with my boyfriend. We're both very happy."
In a Teen Mom episode that was aired earlier this year, the reality star confessed that she and her ex-fiance had talked about having children, however she was worried about being pregnant whilst on medication.
"I just got re-diagnosed for Borderline Personality and Bipolar Disorder, and I've been taking three medications now that I need to take for the rest of my life," Portwood said. "I can't, I can't get pregnant on this medication...I can get pregnant, but it would mess up the fetus. If I do not have medication, I will not be normal. I would have...crazy mood swings."