Maria Antonia grew up with her brother and sisters in the ducal court of Parma, where she was affectionately known as Tognina.

While their parents were allowed to formally remain on their throne but were watched by an entourage of French guards, Maria Antonia and her sister Carlotta were awarded their freedom as they were regarded apolitical.

[2] The sisters remained by the side of their parents as their support during the French occupation: they were both regarded to have the religiosity of their father and the willpower of their mother.

[3] However, while Carlotta was imposing enough for the French governor Andoche Junot to recommend that she be acknowledged a Princess by France and awarded a pension to be able to live according to her status,[4] Maria Antonia was described as particularly severe and reserved.

The following year, on 22 April 1803, she officially received the habit of an Ursuline nun and changed her name to Sister Louise Marie (Luigia Maria).