The Pope said he wanted "to encourage the intellectual honesty of your work, an expression of a science that maintains a correct spirit of seeking the truth to serve the authentic human good and that avoids the risk of being merely functional."

At the conference, physicians and researchers said modern medicine's almost automatic recommendation that couples having trouble conceiving try in vitro fertilization is a response that does not seek the cause of infertility, but addresses only the symptom and does so in a way that violates church teaching.

With in vitro fertilization, a woman's eggs are removed, united with sperm in a laboratory, and then implanted in the womb of the mother or a surrogate. The procedure is costly, and the Catholic Church teaches IVF is immoral because fertilization does not take place through the sexual union of a husband and wife. The church also condemns the common IVF practice of destroying or freezing fertilized embryos that are not implanted.

"In effect, scientism and the logic of profit today seem to dominate the field of infertility and human procreation, reaching a point where it also limits many other areas of research," Pope Benedict said.

The physicians and scientists at the Vatican conference, however, are motivated "by the desire not only to give a couple a child, but to restore the spouses' fertility and the dignity of being responsible for their procreative choices in order to collaborate with God in the generation of a new human being," the Pope said.

Doctors must help fulfill "the legitimate parental aspirations" of a couple dealing with infertility, he said, but they must do so in a way that "fully respects their dignity as persons and spouses."

In addition, he said, Catholic couples need to know that their marital vocation is not diminished if they cannot have children. The couple is still called to love and self-giving, and "to collaborate with God in the creation of a new humanity" and a better world, he said.