Humans intentionally limit the propagation of their race through family planning, abortion, and contraceptives. Genetic engineering will likely intermesh with these to produce "enhanced" or "designed" progeny to specifications.
We must stop procreating. Or, else, pray for a reduction in our numbers.
Yet, the alternative is cataclysmic. Unintended wars, rampant disease, and lethal famines will ultimately trim our numbers - no matter how noble our intentions and how diligent our efforts to curb them.