Six months pregnant Nicole Richie’s previous drug history and a spell of Braxton-Hicks contractions has left the mom-to-be in fear of a miscarriage.

“She’s a basket case, constantly worrying about having a miscarriage, too,” says a Star Magazine source.

“She has her doctor’s number on speed dial and has been calling non-stop. She also found a doctor in Australia who’s available to her 24/7.”

“Her stress level is through the roof.”

Nicole is also in fear of losing the baby after a bout of false contractions, medically known as Braxton-Hicks.

“She felt a deep pain in her lower adomen like her stomach was seizing up. She believed she was going into labor.”