Perhaps you should try some spelling variations:
maternal performance » materials performance, external performance, national performance
performance metrics » performance measures
improving maternal » improve maternal, improving water
improving school » improving schools, improving preschool, improve school

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( improving school performance targets. ) or ( improving maternal performance metrics. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( improving school performance targets. ) OR ( improving maternal performance metrics. )).
• Adding a wildcard symbol may retrieve word variants: (( improving school performance targets. ) or ( improving maternal performance metrics. ))*.