Over the years, the LDS First Presidency has made various statements about sexual relations between husband and wife. Unsurprisingly then, Mormons seem to hold divergent views on this topic. But it is unclear which are the prevailing attitudes today because Mormons are typically tight-lipped when it comes to sexual matters.
A review of First Presidency statements over the past century reveals some interesting historical trends that may shed light on the origins of prevalent attitudes among Mormons today about sexual relations within marriage. In 1905, when Joseph F. Smith was serving as President of the Church, the First Presidency made the following statement:
[T]he Church of Jesus Christ of Latter-day Saints has formulated no special rules governing the associations of married people. . . . [A]s to their mutual conduct in the marital relation, so far as sexual intercourse is concerned, they are left entirely free. 
This view apparently continued to prevail for nearly three-quarters of a century. For example, in 1971, when Joseph Fielding Smith was serving as President, the following response was given to an unspecified question posed by a female church member:
The Brethren feel that the question which you raise is such as should be answered by you and your husband and in accordance with your own convictions. The Church has never believed it necessary to issue instructions pertaining to intimate relations between husband and wife. 
However, the First Presidency’s laissez-faire attitude toward sexual relations between married persons changed during the administration of President Spencer W. Kimball. In 1975, the First Presidency began admonishing married couples against having casual views about sexual relations within marriage:
The union of the sexes, husband and wife (and only husband and wife) was for the principal purpose of bringing children into the world. Sexual experiences were never intended by the Lord to be a mere plaything or merely to satisfy passions and lusts. We know of no directive from the Lord that proper sexual experience between husbands and wives need be limited totally to the procreation of children, but we find much evidence from Adam until now that no provision was ever made by the Lord for indiscriminate sex. 
Another First Presidency statement issued in 1976 suggests this tightened guidance was a reaction to the so-called “Sexual Revolution” of the 1960′s and 70′s : “We live in a culture which venerates illicit sex, streaking, trading wives, and similar crazes. . . . We call upon all of our people to do all in their power to offset this ugly revolution.” 
Under President Kimball’s leadership, the First Presidency provided increasingly specific guidelines to local leaders about questioning members concerning their sexual purity in temple recommend interviews. Local leaders were urged to allow married persons to determine their own purity in regards to their sexual relations with their spouse, but at the same time, the First Presidency took the added step of identifying certain sex acts as being “unnatural, impure, or unholy” practices:
Married persons should understand that if in their marital relations they are guilty of unnatural, impure, or unholy practices, they should not enter the temple unless and until they repent and discontinue any such practices. Husbands and wives who are aware of these requirements can determine by themselves their standing before the Lord. All of this should be conveyed without having priesthood leaders focus upon intimate matters which are a part of husband and wife relationships. . . . The First Presidency has interpreted oral sex as constituting an unnatural, impure, or unholy practice. 
It appears this guidance left local leaders confused about whether to allow married persons to determine their worthiness according to their own personal interpretation of “unholy practices,” or to impose and enforce the First Presidency’s interpretation of it. Just three months after the letter quoted above was issued, the First Presidency issued another letter admonishing local leaders to “never inquire into personal, intimate matters involving a man and his wife,” to stick to the specific questions in the temple recommend book, and to counsel married persons to discontinue sex acts that caused them enough anxiety to ask about their propriety.  It seems this relatively brief detour from the guidance offered by previous First Presidencies on this topic was brought to an end more or less with the death of President Kimball.
For the past two decades, the First Presidency’s guidance about sexual relations between married persons has typically been phrased in terms of the appropriate purposes of sexual relations between husband and wife, as opposed to addressing the appropriateness of specific acts. Here are a couple examples:
[S]exual relations within marriage are divinely approved not only for the purpose of procreation, but also as a means of expressing love and strengthening emotional and spiritual bonds between husband and wife. 
Physical intimacy between husband and wife is beautiful and sacred. It is ordained of God for the creation of children and for the expression of love within marriage. 
Taken collectively, the view that seems to emerge from the statements quoted above is that married persons should have sexual relations either for procreation or to achieve some abstract, non-physical benefit (e.g., “strengthening emotional and spiritual bonds”), but not to “play” or “satisfy passions.” By analogy, one might say it is appropriate to eat food to gain energy to perform one’s labors or to live a long life of service, but not to enjoy its delicious taste or to satisfy one’s hunger pangs.
While the precision of any analogy is always open to debate, it seems safe to say that faithful Mormon couples may find it difficult to implement the above-quoted prophetic counsel on a practical level. Within the context of marriage, it seems extremely difficult to identify the invisible dividing line between sexual relations that create “spiritual and emotional bonding” and those that “satisfy passions.” Likewise, it is unclear what constitutes “indiscriminate sex” between a husband and his wife.
Moreover, despite the First Presidency’s discontinuation of the “Kimball approach” to this subject, one occasionally encounters lingering vestiges of the Kimball administration’s more restrictive views on sexual relations between married persons. Mormons seem to hold differing views about whether married couples are obligated to keep their sexual relations within the more restrictive bounds articulated during the Kimball era. For example, should married Mormons feel obligated to conform to the Kimball administration’s interpretation of “unholy practices,” or its admonitions against “indiscriminate sex” and having sex to “satisfy passions”?
I interested in hearing your views about how faithful Mormons should implement the prophetic guidance quoted above in their marital relationships. I may be unduly naïve and trusting to proffer these questions for discussion, but I truly hope they can be addressed in a respectful and mature manner.
 Gary James Bergera, Statements of the LDS First Presidency, p. 423.
 Id. at 422.
 Id. at 421.
 First Presidency letter, Jan. 5, 1982.
 Gary James Bergera, Statements of the LDS First Presidency, p. 422.
 Church Handbook, 1998.
 True to the Faith, 2004.