A LifeSite article explains that rather than coming out of altruistic motives, developed nations developed a strategy in the 1970's to reduce the birth rates around the world so as to limit competition. This strategy was drafted by Henry Kissinger, and in many ways has been realized through the promotion of abortion and contraception abroad.
Pope John Paul II spoke of this in Evangelium Vitae:
The Pharaoh of old, haunted by the presence and increase of the children of Israel, submitted them to every kind of oppression and ordered that every male child born of the Hebrew women was to be killed (cf. Ex 1:7-22). Today not a few of the powerful of the earth act in the same way. They too are haunted by the current demographic growth, and fear that the most prolific and poorest peoples represent a threat for the well-being and peace of their own countries. Consequently, rather than wishing to face and solve these serious problems with respect for the dignity of individuals and families and for every person's inviolable right to life, they prefer to promote and impose by whatever means a massive programme of birth control. Even the economic help which they would be ready to give is unjustly made conditional on the acceptance of an anti-birth policy. -Pope John Paul II, Evangelium Vitae 16A way in which this plan has backfired is the demographic decline of the Western world. The birthrates of European nations have fallen below replacement levels. The European average of 1.3 children/woman falls well below the 2.1 needed to sustain the population. The Russian population is expected to decline by a third by 2050. Here in America, it's right at 2.1, but that is largely due to higher birthrates among immigrants. At some point in this century, the world's population is going to plummet dramatically. Economies will follow if there are not enough people to sustain them. Our own country's strategy could prove to be its undoing. This topic is explored in the documentary Demographic Winter.
Whether it is in developed or developing countries, we should not view this decline as a positive. All should be welcome at the table of life, and policies that attack human life will have disastrous results.