Complex sentence: Jane Austen was born at Steventon on 16 December 1775, a month later than her parents expected according her father's assertion in a letter that her mother "certainly expected to have been brought to bed a month ago".
Split into simpler sentences: Jane Austen was born at Steventon on 16 December 1775. She arrived a month later than her parents expected; her father wrote of her arrival in a letter that her mother "certainly expected to have been brought to bed a month ago".