These countries are doing this out of a sense of patriotism and as an attempt to preserve culture, not to benefit the earth or the human race overall. Overpopulation is and will continue to be a problem overall which is the point that was being made. As you stated, some women in the world have 7 kids each so on the whole the world population is growing.
But I'm thinking long term and in a bit more complex terms. There is no "overpopulation" as such, and I refuse to engage in the politically correct resource scarcity hysteria.
In 2050 (very soon), world population levels will have reached their peak at 9 billion (4th revision of the UN World Population Prospects). From 2075 onwards, a global decline sets in. But this progress is conditional.
We only get there when we produce enough smart brains that develop smart technologies. These smart babies are grown in countries like Japan, Russia, the US and the EU. It is crucial to maintain population levels there, otherwise developing countries will live in eternal misery; it's the highly developed, post-industrial world that delivers the technologies needed so much by the developing world. Else, sustainable development will never happen and we will continue to see a demographic explosion.
In short, a population decline in the post-industrialised world, as we are seeing today, is extremely dangerous for the health of the planet and will lead to a population time bomb that will destroy Earth.
(That's why the UN makes demographic projections on the basis of parameters such as economic growth and the intensity of the growth in technologies and tech transfers).
Or do you want farmers in developing countries to keep chopping down rainforests simply because they don't have access to modern infrastructures, technologies and agricultural knowledge?
If Veronica_Divine decides not to make kids, we miss a perfect opportunity to have a much needed engineer, scientist or entrepreneur - needed to make life on the planet sustainable. One smart engineer in the West can develop breakthrough technologies that can help entire countries reduce their fertility rates.
Just think of the invention of the pill: a few smart people developed this breakthrough. You know the results.
If Veronica_Divine's baby happens to be the engineer who develops a new genetically modified strain of manioc that yields more per hectare, the population in Africa would drop at once due to increased food security.
Common Veronica, we need your divine womb to do its duty! Give us a bio-engineer! You can do it!!