Actually, the "Responsible Child-bearing in the Time of the End" talk was given in the 1987 "Trust in Jehovah" district convention (in the afternoon of day #2) and was published in the 1 March 1988 Watchtower (pp. 23-27).
That is the big talk that stands out in my mind too.
Also, Rutherford especially started discouraging childbearing in the 1938 "Fill the Earth" Watchtower articles, I don't know off hand of earlier statements to this effect.