If a woman who converted orthodox is living a modern lifestyle (keeps Shabbos and kosher but is very lax about it and doesn't keep every halacha) but her child is not religious at all, is the child considered a non Jew? The child was born after the mothers conversion.
If a woman converts to Judaism while pregnant, will her child be a Jew? states that if a woman converts while pregnant, the child is Jewish. If she becomes pregnant after she has converted, then of course the child is Jewish. If the conversion was not valid to begin with, the she was never Jewish and neither is the child.