Chinese tourists had originally been able to stay in the CNMI for up to 45 days.
However, Governor Ralph Torres made a call to cut their stay to address the issues of 'birth tourism' and overstaying.
US Customs and Border Protection have made the changes, which will come into effect on Thursday.
'Birth tourism' is used to describe the practice of travelling to another country for the purpose of giving birth to obtain citizenship.
The Commonwealth Health Care Corporation says last year the number of tourists who gave birth in the CNMI was at 582, an increase of 21 from the previous year.