Here are some quotes from a Google search:
"the child of a mixed marriage" (509 returns)
Being the child of a mixed marriage myself (my mother was British while my father was American), I was somewhat aware of the process already.
If the child of a mixed marriage has been brought up and educated as a Jew and becomes a Bar or Bat Mitzvah, or otherwise demonstrated his or her commitment to Jewish identity and knowledge, then a progressive synagogue will accept that person as a Jew in good faith.
First, Edmund Burke was a Christian, despite the doubts that critics have expressed about his faith. But he was the child of a mixed marriage between a Catholic mother and a Protestant father, a member of the Established Church of Ireland.
So, both are used.
Rusesabagina tells for the first time the full story of his life---growing up as the son of a rural farmer, the child of a mixed marriage
, his extraordinary career path which led him to become the first Rwandan manager of the Belgian-owned Hotel Milles Collines---all of which contributed to his heroic actions in the face of such horror.
"a child of a mixed marriage" (165 returns)
“This leads us to the conclusion that the same requirements must be applied to establish the status of a child of a mixed marriage, regardless of whether the mother or the father is Jewish.”
A child of a mixed marriage, Halina was only 13 when the war began. She was interned in the Warsaw ghetto and the Stuthof Concentration Camp.
I am a child of a mixed marriage - but my father, whose family is Muslim, has always entered his ethnicity as Serb and his religion as Muslim when asked for this information in Yugoslavia's official documents.
Like me, a child of a mixed marriage between a Serb and a Muslim, Silky was forced into immigration.
Ten years ago on March 15, 1983, the Reform Central Conference of American Rabbis issued a resolution which equated matrilineal and patrilineal descent. A child of a mixed marriage is to be regarded as Jewish whether the father is Jewish or the mother is Jewish, the presumption is that the child is Jewish. That Reform resolution went on to state that this presumption of the Jewishness of the child is to be "established through appropriate and timely public and formal acts of identification with the Jewish faith and the Jewish people."