IVF and almost all the treatments available in fertility clinics necessitate the deaths of many human beings at the embryonic stage of life. Typically, IVF treatments involve the creation and destruction of dozens of human embryos to get one positive result.
The idea that there can be sound reasons, based on hard medical and scientific facts, behind moral objections to anything is one that the modern mind has great difficulty grasping.
It is simply a myth, generated by the abortion industry, that "science does not know when human life begins". This myth can be refuted by opening any first-year university text on human embryology. They all agree that the zygote, the human embryo at the first, single-cell stage of existence, is fully a human being. It is genetically distinct from the mother, it is either male or female, it respirates and consumes nutrients separately, it has every part of the genetic make-up of the adult and its growth is ordered according to that genetic information. It is the same being as the foetus, the infant, the child, the adolescent and the adult it will potentially become. The zygote, therefore, is not a "potential human"; it is merely a "potential adult".
As the Catholic Church put it in its seminal document Donum Vitae
("the Gift of Life"):
"The child has the right to be conceived, carried in the
womb, brought into the world and brought up within marriage: it is through the
secure and recognized relationship to his own parents that the child can discover
his own identity and achieve his own proper human development."
This simple, clear statement is the key to the whole puzzle of why there is
a moral objection to artificial procreation. Artificial procreation techniques
may indeed result in giving some couples children they wouldn't otherwise have,
but the cost is too high.
These techniques violate the rights of a person so created to be conceived naturally in marriage, to be gestated by his mother, to be born, and to live. It does not have to be more complex than that.
Based on universally accepted scientific criteria, a new cell, the human zygote, comes into existence at the moment of sperm-egg fusion, an event that occurs in less than a second. Upon formation, the zygote immediately initiates a complex sequence of events that establish the molecular conditions required for continued embryonic development. The behavior of the zygote is radically unlike that of either sperm or egg separately and is characteristic of a human organism. Thus, the scientific evidence supports the conclusion that a zygote is a human organism and that the life of a new human being commences at a scientifically well defined “moment of conception.”
Listen to this interview with Robert P. George, who says "at all stages of our lives — from the embryonic through the fetal, infant, child, and adolescent stages and into adulthood — we are human beings with dignity and the right to life. Our dignity does not come from having achieved a certain level of intellectual proficiency or even conscious awareness. … We have our dignity in virtue of the kind of entity we are: that is human being, a creature with a rational nature. And we became that when we came to be."
Life Principles by Robert J. Spitzer, Ph.D
Raymond Dennehy, "THE ONTOLOGICAL BASIS OF HUMAN RIGHTS", The Thomist 42 (July 1978): 434-463.