http://jwfacts.com/watchtower/quotes/marriage-child-bearing.php
Watchtower 2000 August 1 p.21 Why Do They Have No Children?
"Although Noah's three sons were all married, none fathered children until after the Deluge. ? While this does not imply that it is wrong to have children today, many Christian couples decline to have children so as to become more fully involved in the urgent work that Jehovah has given his people to do. Some couples have waited for a time before having children; others have decided to remain childless and consider the possibility of bearing children in Jehovah's righteous new world."
Watchtower 1988 March 1 p. 19 Childbearing Among God's People
"If the expansion of Christianity was to come about mainly by childbearing, Jesus would not have encouraged his disciples to "make room" for singleness "on account of the kingdom of the heavens." (Matthew 19:10-12) ?
How should Christians view marriage and childbearing today, in this "time of the end"? (Daniel 12:4) It is truer than ever that "the scene of this world is changing," or, as another translation puts it, "the present scheme of things is rapidly passing away."-1 Corinthians 7:31, Phillips. Now, as never before, "the time left is reduced." Yes, only a limited time remains for Jehovah's people to finish the work he has given them to do, namely: "This good news of the kingdom will be preached in all the inhabited earth for a witness to all the nations; and then the end will come." (Matthew 24:14) That work must be accomplished before the end comes. It is, therefore, appropriate for Christians to ask themselves how getting married or, if married, having children will affect their share in that vital work. ?
During all this pre-Flood period, Noah's sons and their wives had no children."
Awake! 1974 November 8 p.11
"Today there is a great crowd of people who are confident that a destruction of even greater magnitude is now imminent. The evidence is that Jesus' prophecy will shortly have a major fulfilment, upon this entire system of things. This has been a major factor in influencing many couples to decide not to have children at this time. They have chosen to remain childless so that they would be less encumbered to carry out the instructions of Jesus Christ to preach the good news of God's kingdom earth wide before the end of this system comes. -Matt.24:14."
Children (1941) 3,000,000 ed. pp.312-313
"Should men and women, both of whom are Jonadabs or "other sheep" of the Lord, now marry before Armageddon and bring forth children? They may chose to do so, but the admonition or advice of the scriptures appears to be against it.
Face the Facts (1938) pp.46-50
"Would it be Scripturally proper for them to now marry and to begin to rear children? No, is the answer, which is supported by the Scripture?. Those Jonadabs who now contemplate marriage, it would seem, would do better if they wait a few years, until the fiery storm of Armageddon is gone..."
Watchtower 1938 November 1 p.324
"...mark the words of Jesus, which definitely seem to discourage the bearing of children immediately before or during Armageddon
Golden Age 1937 January 27 edition "That Delusion Called Love"
"God's consecrated people do well to refrain from marriage unless they find themselves continually tormented with desire for sexual intercourse, in which case they should marry. ? For those of the younger or older who have need to marry on this score, let them dispose of the matter in candor and honesty ? shunning the blight, the delusions and illusions of "love" so called and courtship, which bring reproach on the holy name of Jehovah."
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Also the reasoning was that Noah's sons (and daughter-in-laws) did not have children before the flood and the WTS implies it was by choice although the BIBLE DOES NOT SAY. Rutherford believed that WW2 would culminate in Armaggedon.
There was also back and forth discussion of what the "procreation mandate" was and when it would begin.
http://www.quotes-watchtower.co.uk/children.html
1938 "Would it be scripturally proper for them to marry and begin to rear children? No, is the answer, which is supported by the scriptures....I will be far better to be unhampered and without burdens, that they may do the Lords will now, as the Lord commands, and also be without hindrance during Armageddon. … Those... who now contemplate marriage, it would seem, would do better if they wait a few years, until the fiery storm of Armageddon is gone." (Face the Facts, 1938, p. 46, 47, 50)
1941 Should men and women, both of whom are Jonadabs or "other sheep" of the Lord, now marry before Armageddon and bring forth children? they may chose to do so, but the admonition or advice of the scriptures appears to be against it. (Children; 1941; 3,000,000 ed.; p. 312)
1941 The prophetic picture seems to set forth the correct rule, to wit: The three sons of Noah and their wives were in the ark and were saved from the flood. They did not have any children, however, until after the flood. They began to have children two years after the flood. (Genesis 11:10,11) No children were taken into the ark and none were born in the ark, and hence none were brought out of the ark. Only eight persons went in and eight came out of the ark. (1 Peter 3:20; Genesis 8:18) That would appear to indicate that it would be proper that those who will form the "great multitude" should wait until after Armageddon to bring children into the world. (Children; 1941; 3,000,000 ed.; p. 312-313)
1941 "Armageddon is surely near, and during that time the Lord will clean off the earth everything that offends and is disagreeable. ... From now on we shall have our heart devotion fixed on The Theocracy, knowing that soon we shall journey forever together in the earth. Our hope is that within a few years our marriage may be consummated and, by the Lord's grace, we shall have sweet children that will be an honor to the Lord. We can well defer our marriage until lasting peace comes to the earth." (J. F. Rutherford, Children, 1941, p.366)