Marriage was ordained by God and it is clear in the Genesis account that woman was not create solely for the purpose of propagation of the race but for the outworking of man’s social relationship in companionship and love. …
The Bible clearly teaches that sexual union has purposes other than procreation. Indeed, Paul implies that frequent sexual intercourse in marriage is natural and indeed, advisable.
C. Everett Koop, Birth control and the Christian: A Protestant Symposium on the Control of Human Reproduction; cited in Wycliffe Dictionary of Christian Ethics, Carl F.H. Henry editor, pg.137.