Perhaps you should try some spelling variations:
"improving maternal performance metrics." » "improving national performance metrics.", "improving thermal performance metrics.", "improving lanterns performance metrics.", "improving maternal performance contracts.", "improving maternal performance contract.", "improve maternal performance metrics.", "improving water performance metrics."
"improving rural performance measures." » "improving pupil performance measures.", "improving thermal performance measures.", "improving overall performance measures.", "improving urban performance measures.", "improving social performance measures."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving maternal performance metrics.") OR ("improving rural performance measures."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving maternal performance metrics.\") OR (\"improving rural performance measures.\"))".
• Removing quotes may allow a broader search: (( improving maternal performance metrics. ) OR ( improving rural performance measures. )).
• Adding a wildcard symbol may retrieve word variants: (("improving maternal performance metrics.") OR ("improving rural performance measures."))*.