It's a reduction in the amount or quality of something.
Decline
A gradual change or development that produces a particular result.
A trend
The practice of controlling the number of children that you have by using contraceptives.
Family planning
It's the number of deaths of children under a year old in a particular society.
Infant mortality
It's the length of time that someone is likely to live.
Life-expectancy
To become larger in amount or number.
To increase
To become less.
To decrease
Existing in small amounts, or very spread out.
Sparse
