Complex sentence: Hobbs had migrated as a girl to the Illinois country with her parents, but returned to Philadelphia to study medicine: her studies included nursing, midwifery and dental extraction, the sum of what women at the time could study in medicine.
Split into simpler sentences: Hobbs had migrated as a girl to the Illinois country with her parents. She returned to Philadelphia, Pennsylvania to study medicine: her studies included nursing, midwifery and dental extraction, the sum of what women at the time could study in medicine.