One of the best ways to reduce the number of children born (according to sachs) is to:

I believe the answer is: decrease infanticide
Infanticide refers to the act of taking the life of infants on purpose.
According to sachs, decreasing infanticide would improve parents' awareness on the value of infants life, which more likely to make them think twice before producing one.

It should be at the center of any map going vertically: the prime meridian, as it passes through greenwich,  england, is considered 0 degrees longitude