Widow/Orphan Control dialog box
Custom Toolbar > Page Break > Widow and Orphan Control
(Customize dialog box > Format > Page Break)
Prevent widows
Select this check box to prevent automatic page breaks from happening too close to the tops of paragraphs. Specify the minimum number of lines of a paragraph that must fall after a page break.
Prevent orphans
Select this check box to prevent automatic page breaks from happening too close to the ends of paragraphs. Specify the minimum number of lines of a paragraph that must fall before a page break.