Perhaps you should try some spelling variations:
"improving maternal performance metrics." » "improving materials performance metrics.", "improving external performance metrics.", "improving national performance metrics.", "improving maternal performance measures.", "improve maternal performance metrics.", "improving water performance metrics."
"improve company performance reviews." » "improve country performance reviews.", "improve company performance review.", "improve company performance reports.", "improve company performance risks."

Try widening your search to All Fields.

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 ("improve company performance reviews."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving maternal performance metrics.") OR ("improve company performance reviews.")).
• Removing quotes may allow a broader search: (( improving maternal performance metrics. ) or ( improve company performance reviews. )).
• Adding a wildcard symbol may retrieve word variants: (("improving maternal performance metrics.") or ("improve company performance reviews."))*.