Image Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team
Answer. Posted on Sunday, May 3, 2015.
New stars need hydrogen to begin the nuclear fusion process by which hydrogen atoms join together to form a helium. The fusion process powers the stars during the Main Sequence period where they spend most of their lifetimes.
Hydrogen is the most common element in the universe. However, in order to form stars, there must be enough hydrogen in an interstellar cloud for nuclear fusion to start.
Thereby, if it is not enough hydrogen for fusion to start, then there are no more new stars!