I was sure this was an Arthur C. Clarke short story, but websearching the book I was looking for led me to 'The Vitanuls' By John Brunner, a story where an Indian Physician discovers that the reason babies are being born without souls is that the world population has increased over the available soul stock. His response is, rather than to spray a cockroach habitat with insecticide, releasing a large number of substandard souls for recycling (umm, that's me, not the original story) to commit suicide thus alowing a body with a decent hope of ascension onto the wheel.