In 2373 the Q Continuum fell into civil war between traditionalists and Q who wanted change, causing supernovae across the galaxy until a child was born.
After the suicide of the Q called Quinn, the Continuum split between those who wanted to preserve its old order and those, led by Q, who wanted change. In 2373 their struggle spilled into the physical universe, setting off supernovae. Q sought out Janeway, hoping a child combining Q and human qualities would end the conflict.
Janeway refused, and the Voyager crew entered the Continuum, which they perceived as a battlefield like the American Civil War. They helped rescue Q, and he and Female Q had a child, ending the war.