Poland’s Catholic bishops have warned government leaders and legislators not to back a law allowing in vitro fertilization, adding that the practice resembled Nazi-era eugenics.

“The in vitro method incurs huge human costs — the birth of one child requires in each case the death, in various stages of the medical procedure, of many living beings,” the bishops’ conference president, Archbishop Jozef Michalik, said in a letter to Polish government leaders and legislators.

“While sympathizing with families suffering infertility, we voice acknowledgment for all those who, despite personal drama, seek to stay faithful to the principles of Christian ethics and are open to accepting children through adoption.”

The letter said the process had “incalculable social consequences” because it created multiple mothers and anonymous donors of genetic material, some of whom demanded alimony payments.

“Separating procreation from the marriage act always has bad social effects and is especially unfavourable to children coming into the world,” it said.