JOEL - So far God has not yet revealed to us the exact moment a spirit enters the body of an individual to begin a living soul. Some believe it happens at conception, some during gestation in the womb, and some believe it happens at birth with the first breath of life. According to the Church Handbook of Instructions, "It is a fact that a child has life before birth. However, there is no direct revelation on when the spirit enters the body."(page 157)
According to Russell M. Nelson:
"It is not a question of when “meaningful life” begins or when the spirit “quickens” the body. In the biological sciences, it is known that life begins when two germ cells unite to become one cell, bringing together twenty-three chromosomes from both the father and from the mother. These chromosomes contain thousands of genes. In a marvelous process involving a combination of genetic coding by which all the basic human characteristics of the unborn person are established, a new DNA complex is formed. A continuum of growth results in a new human being. The onset of life is not a debatable issue, but a fact of science." (Russell M. Nelson, “Reverence for Life,” Ensign, May 1985, 11)
So according to Elder Nelson and biology, life begins at conception; but that still does not tell us when the spirit enters the body.
As I have stated elsewhere, one can argue that the spirit probably does not enter a fertilized developing embryo until it has at least implanted itself in the mothers womb. It is not uncommon for an embryo to fail to implant itself, so it would therefore be illogical for the spirit to have already united with it before that happens. Also, during the time between conception and implantation, embryos can not yet be considered as individualized human life, since they still possess the potential to combine, or split. It is also possible to store embryos in a frozen state, thaw them out later, and succesfully implant them in a mother's womb. Has the spirit already entered an embryo that is being stored in a freezer at -70 C? I doubt it.
The fact that Jesus Christ announced his birth to Nephi only a night before the event, suggests that the spirit enters the body at birth. (3 Nephi 1:13) But of course Christ was a God and probably could have come and gone out of His body anytime He wanted.
Past Church leaders have had their own opinions on this matter.
President Brigham Young said he believed that “when the mother feels life come to her infant it is the spirit entering the body.” (Journal of Discourses, 17:143.)
The message “The Origin of Man” issued by the First Presidency in 1909 stated: “The body of man enters upon its career as a tiny germ embryo, which becomes an infant, quickened at a certain stage by the spirit whose tabernacle it is, and the child, after being born, develops into a man.” (James R. Clark, comp., Messages of the First Presidency of The Church of Jesus Christ of Latter-day Saints, Salt Lake City: Bookcraft, 1970, 4:205.)
Elder Bruce R. McConkie, referring to “The Origin of Man,” expressed his opinion that the message “appears to bear out the concept that the eternal spirit enters the body prior to a normal birth, and therefore that stillborn children will be resurrected.” (Mormon Doctrine, 2d ed., Salt Lake City: Bookcraft, 1966, p. 768.)
Other Church leaders have suggested that a living soul does not exist until three essential elements—the body, the spirit, and the breath of life—are all present.
The question of whether miscarried and stillborn children will be resurrected and belong to their parents in the hereafter is impossible to answer with certainty. Elder Joseph Fielding Smith seems to agree with Elder McConkie when he wrote that “there is no information given by revelation in regard to the status of stillborn children. However, I will express my personal opinion that we should have hope that these little ones will receive a resurrection and then belong to us.” (Doctrines of Salvation, 2:280.)
But no one has said this about miscarried fetuses. The definition of a miscarriage is the delivery of a dead fetus, before it is viable—that is, before it could have lived on its own outside the mother’s womb. It seems unlikely that God would place a spirit into a body that He knew was never going to make it to a stage where it could live on its own. But then who am I to comprehend the mind and will of God?
Of course whether a baby is miscarried or stillborn the effects on the mother are still devastatingly tragic and emotionaly upsetting. They grieve almost the same as if it were one of their live children who died. They sometimes feel certain that the spirit of their child was with them during the pregnancy. Some feel that the spirit of a baby that went full term and was born is the same one that miscarried during an earlier pregnancy. Are these mothers right?
As far as church records are concerned, if a stillbirth takes place after the parents are sealed in the temple, those children can be identified on the record as being born in the covenant and the family may give a stillborn child a name and even hold funeral services if they desire. Miscarriages, however, are usually not recorded on family group records. (Church Handbook of Instructions, p. 157)
If stillborn or miscarried children are to be considered as complete souls, Joseph Smith taught the comforting doctrine that the infant child that is laid away in death would come up in the resurrection as a child; and, pointing to the mother of a lifeless child, he said to her: “You will have the joy, the pleasure, and satisfaction of nurturing this child, after its resurrection, until it reaches the full stature of its spirit.” There is restitution, there is growth, there is development, after the resurrection from death. I love this truth. It speaks volumes of happiness, of joy and gratitude to my soul. Thank the Lord he has revealed these principles to us. (Gospel Doctrine, 455-56)
My own personal opinion is that the spirit probably does not enter the body at least until sometime after the fetus has matured to a point where it could live outside the body, perhaps when the mother first feels the baby move.