Tonight, Discovery Health will air the documentary I'm Pregnant And... I Have An Eating Disorder. In a preview from GMA, Beth Jones struggles to eat enough for her unborn child, even when doctors tell her the baby is too small.

Beth, who has battled anorexia, bulimia, and excessive exercising for 25 years, is not one of those women. In a therapy group for pregnant women with eating disorders, Beth explains what's going through her head: "This baby's going to come and you're going to be big and fat. Who are you going to be if you're big and fat? That's just not acceptable, sorry."

Luckily, Beth's baby is born at a healthy weight and she plans to continue treatment. However, her husband Mike worries about the effect her eating disorder may have on their three children. He breaks down as he says, "Kids pick up on everything. its something we are extremely aware of and I will be extremely sad, especially if my daughter... if they would ever have to go through that."

Pregnant With An Eating Disorder: "I Want To Get Well" [ABC News]

Earlier: New Standard For Obese Women: Zero Weight Gain During Pregnancy