If there's ever an ethical issue, its abortion. And abortion is an especially interesting topic in Mormonism, much more complex than in mainstream Christianity.
Now while it is obviously clear that Mormonism would adamantly oppose abortion for reasons of convenience (to do so could even amount to disciplinary action by the church), it also allows for some situations of acceptable abortion such as incest, rape, or danger to the mother. But generally, in most cases the church encourages a couple to marry and begin to work towards temple marriage, or when a marriage is not in the picture, to carry the baby to term and give it up for adoption.
With that said, there is a whole host of issues that are brought up because of unique Mormon beliefs related to abortion and fetus issues.
When does the spirit enter the body?
We know that when a child is born and alive it has a spirit, unique to them, that came through the veil from the spirit world. But when does that event occur?
In the message "The Origin of Man" issued by the First Presidency it states, "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." This address was given in 1909 and for the past 100 years there has been no further clarification on what that statement means or what that doctrine means for the church. Since that time opinions, policies, and stories come out which I have gathered into what I see as 4 opinions on when the spirit enters the body, and what effect that has on actual real life ethical situations.
#1 - In order to be a living soul, there must be a body, spirit, AND the breath of life. Thus stillborns/miscarriages never received the breath of life, and never were a living soul. No temple work is done, and although the experience is traumatizing for the mother and father, the grief is for the opportunity of life, not grief for the actual loss of a member of the family because they were never truly alive. There is some doctrine supporting this with the study of Adam who lived when he received his body, spirit, and breath of life. Women who mourn over a miscarriage or stillbirth feel the pain because of the deep rooted desire to have children, and this can cause them to feel that the dead embryo is part of the their family in an effort to combine their experience with their religion in a way that relieves pain. But the child was actually never alive and not part of that eternal family. Also it should be noted that if the baby is born and breathes a natural breaths and then dies, it is given a name, blessing, funeral and is recorded in the church.
#2 - Stillborns and late miscarriages (around the time of 20 weeks) had a spirit and a body and were alive. They were souls so pure that they only needed to enter a body for a period so short in time, they actually never even needed to be born. Temple work and records are not kept for these spirits because of the complications related to it such as far if the fetus had a spirit, if the woman was actually pregnant, how many fetuses were in the womb, etc. Due to the nature of tracking these children, their work will be done in the Millennium, and parents who experienced a stillbirth will be able to raise that child at that time. This idea is the most popular to those who have undergone a stillbirth due to the opinion of Joseph F. Smith who said, "I will express my personal opinion that we should have hope that these little ones will receive a resurrection and then belong to us. I cannot help feeling that this will be the case." This is also supported by the opinion of Brigham Young who thought that women have the ability to feel when the spirit enters the fetus. Some women say they have felt it but the vast majority do not. Elizabeth's womb with John the Baptist leapt when hearing of the Christ child, implying a spirit present at the stage when a mother can feel kicking. Parents of stillborn children often add those children to their personal family records even though they are not on church records for future records.
#3 - Stillborns and miscarriages are from tabernacles not suitable for life, and thus did not have a spirit placed in them by divine design. Adam's spirit after all was placed into his body from Heavenly Father. Bodies are prepared to house our spirits, and when that house is broken, or will be broken, a precious spirit is not placed in it. This idea is supported mostly because of the fact that the church will not add births or deaths of stillborn children or allow temple work to be done on their behalf. According to the church they simply do not exist. It is also supported by the idea that the church is accepting of procedures like in-vitro, which has a high miscarriage rate during the process, and that the church is accepting of rare occasions in which abortion is approved. These policies imply that there is no spirit in the fetus. The other spin-off variation of this opinion is that the spirit entered the fetus at one point, but when the tabernacle failed, it was moved onto another pregnancy in that family or another family so it could have the opportunity of having a body that is independent from the mother. In this opinion God is directly over the placing of spirits, as his fatherly roles are the only ones he does not delegate to Christ or the Holy Ghost, as made clear in the temple.
#4 - Spirit must be present in order for there to be life, and life begins at conception. All things were spiritually made before they were physically made after all. A fetus feels and experiences and has memories, and that spirit is there from the moment of conception. An abortion except in cases where it would kill the mother is actually killing another human soul. The church allows abortions for those involved in incest and rape but only out of pressure to do so, the best thing to do is to give the baby up for adoption in those circumstances. The church does not record the miscarried spirits is because of the unknowns involved in the process of temple work, but these are spirits that are part of the family of the mother and father. This opinion creates the strongest support for "Right to Life" discussions and politics. This view also implies that our families are much bigger than we realize. The average woman has 8 miscarriages in her life, all of which would be her children. Some have even more. Those who undergo fertility procedures may have children in the hundreds from fertilized eggs that never implanted or were discarded. There are some journal recordings and stories of mothers who have been visited in a vision or dream by a child they miscarried that support this idea. The most popular was a bestseller book titled, "Heaven is For Real" where a boy has a near death experience and describes in detail his surgery, heaven, his grandpa, and his two sisters....though the parents did not know the sex of the two miscarriages they had, nor did they tell the boy. Some also interpret the very strong discouragement of the church against surrogacy, egg donation, sperm donation, or use of other's eggs or sperm as a sign that spirit enters at conception.
How you answer the question of when the spirit enters the body has an affect on how you view abortion, how you view issues of infertility, and how you would cope with the situation were it to happen to you. There is no clear doctrine on the matter, and these 4 beliefs that I have gathered are what has come out of the opinions and policies we currently have. And though it is easy to say "God is in charge, we don't have to know, the good Lord understands, etc."....whichever belief system you have in place does have an effect on how you live your life today. It may even have a profound significance sometime in your life. An uncle rapes your daughter and she gets pregnant. You cannot naturally have children and yet want to have a family so badly you begin fertility treatments and create as many fertilized embryos for freezing as you can. A fetus has early genetic testing done in utero and discovers it has chromosome abnormalities that will not sustain life. You or your wife has a miscarriage and you knew what sex it was. You go to the hospital ready to have your baby after 9 months of pregnancy and the cord wraps around the baby's throat during delivery. These things have all happened to Mormons. So, what do you think?