A lonley future

In the far distant future, humanity had created a method of automating the process of childbirth. Taking mandatory “donations” from the healthy populations, sperm and eggs are put into facilities where they are artificially “grown” into the next generation of people. The story starts when our main protagonist is born in one of these facilities, then finds out that they are the last remaining human on earth. The rest of humanity had left earth decades prior to seek refugee in other planets after pollution got to a point of nearly no return and natural resources nearly completely depleted.