What country requirement does the us lack ?

The United States lacks paid parental leave.

Explanation:

Over 40 developed and developing nations around the world have provisions protected by law to grant paid parental leave for undisturbed and unhindered early nourishment of the children. The European countries like Estonia, Bulgaria, and Hungary grant strictly paid parental leaves of about 70 to 80 weeks beginning from the early months of pregnancy. Despite having demanded by women activist groups from across the US, the US hasn't yet taken the issue of making provisions for paid parental leaves.

Interpreting the results of his experiment : )