Pope Benedict XVI said Monday that embryos developed for in vitro fertilization deserve the same right to life as fetuses, children and adults - and that the right extends to embryos even before they are transferred into a woman's womb.
The Vatican has long held that human life begins at conception, but the pope's comments were significant because he specified that even an embryo in its earliest stages - when it is just a few cells - is just as much a human life as an older being.
The pope made the comments during an audience with members of the Pontifical Academy for Life, who opened a Vatican-sponsored conference Monday on the ethics surrounding the handling of embryos before they are implanted during in vitro procedures.
The Vatican opposes in vitro procedures because embryos created in a laboratory are often discarded, whereas others are frozen and still others are created solely for experimentation or to create stem cells.
Pope Benedict repeated the Roman Catholic Church position that life begins at the moment of conception and deserves to be respected and protected from that moment on - a position set out most authoritatively in the 1995 encyclical Evangelium Vitae.
That encyclical did not specifically address the status of an embryo before it is implanted after in vitro fertilization - the two or three days of growth in a laboratory during which the fertilized egg is dividing into a group of cells that are transferred by a doctor into a woman's uterus.
While there is no consensus among scientists about when life begins - and thus deserves legal protection - many scientists believe life starts when the first neurological tissues are evident, about two to three weeks after fertilization, said Dr. Jacques Cohen, a reproductive scientist in New York who was not at the conference. Cohen runs the largest pre-implantation genetic diagnosis group in the United States, Reprogenetics, as well as the Galileo Research Laboratories, which researches embryonic development.