How any sets of quadruplets are there in the world?

The exact number of sets of quadruplets in the world is difficult to determine, as it varies by region and over time due to factors like fertility treatments and overall birth rates. However, quadruplets are quite rare, occurring in approximately 1 in 700,000 to 1 in 1,000,000 births. Given the global population and birth rates, there are likely several thousand sets of quadruplets worldwide at any given time.