Exactly, birth rates that low will lead to mass extinction of entire nations!
A fertility rate below 1.6 means 50% less new people after three generations, say 100 years. Below 1.2 means an 80% drop.
The U.S. is at 1.64. China, Japan, Poland, Spain all below 1.2. South Korea is at 0.7—96% drop.
Mass extinction numbers.