Sergine and Joel Le Moaligou, who only breast fed their daughter, went on trial in France Tuesday on charges of "neglect or food deprivation followed by death," Radio France Internationale reported.
The couple face a possible 30 years in prison if convicted.
Stephane Daquo, the attorney for the mother, said the couple's mistake was not following a doctor's advice to hospitalize their daughter when her six-month check-up indicated she was losing weight and suffering from bronchitis.
An autopsy showed the baby had vitamin A and B12 deficiencies that experts said increased her sensitivity to infection.
Daquo said the parents are completely aware of the mistake they made.
The couple has a 13-year-old daughter who does not suffer from any vitamin deficiencies.