[Heber J. Grant]
We have never presumed to tell Church members how large their families should be. That is a matter that people must decide for themselves and accept the responsibility for their decision. We have always advocated large families under normal conditions. Of course, ill health, disease, and perhaps other conditions may be justifiable reasons for restrain in such matters. The first great commandment given to Adam and Eve was to multiply and replenish the earth. The teachings of the Church are reasonably clear upon the subject, but it is worth considering whether or not we should not avoid extremes in pressing our doctrines.
[Heber J. Grant, Letter to Samuel F. Smith, as quoted in Minutes of the Apostles of The Church of Jesus Christ of Latter-day Saints, 1910-1951, Privately Published, Salt Lake City, Utah 2010]