Name the reading problem, not only the term
Publishing references do not always agree on which isolated line is the widow and which is the orphan. The practical problem is clearer: a reader reaches a page boundary and finds a fragment without enough context. Short final lines at a page top look especially weak, while a single opening line at a page bottom asks the reader to turn immediately.
Headings can be orphaned too. A subhead should keep with at least a useful amount of following text, and a scene-break ornament should not be stranded without prose on both sides.
Fix the paragraph before forcing the page
Professional typesetting balances several controls: paragraph line breaking, hyphenation, tracking within a narrow tolerance, small space adjustments, keep rules, and occasionally editorial rewrites. The best correction is the one a reader does not notice. Adding a blank line or a local font-size change may solve one page while visibly breaking the system.
Work across the spread. Pulling one line backward changes the facing page and every later page in the chapter. An automated paginator can reject poor breaks, but a human should still inspect pages with extreme looseness, stacked hyphens, very short last lines, or suspiciously large bottom space.
Know when a short page is correct
A short last page at the end of a chapter is natural. A page preceding a fixed recto opener may also finish early. Do not stretch paragraphs simply to make every bottom edge equal. Consistency of rhythm matters more than a mechanical rectangle.
The problem is unexplained variation: an ordinary body page ending several lines early because a heading was kept with too much text, or a chapter with one compressed page surrounded by comfortable pages. Proof diagnostic outliers in context.
EPUB behaves differently
A reflowable EPUB cannot promise fixed widow and orphan outcomes because the reader controls the font, width, and size. CSS can request limited widow and orphan behavior, but reading-system support varies and rigid rules can create excessive blank space on small screens.
Prioritize semantic grouping, sensible paragraph structure, and robust headings. Test large text and narrow screens, then allow the device to paginate instead of hard-coding print line breaks into the ebook.
Sources: Amazon KDP: Format Your Paperback · W3C: EPUB 3.3. Reviewed ; recheck current platform requirements before production.