I don't know the relationship high population growth and poverty. But I think you want it to at a maximum be the same as GDP growth. I would also go for lower population because I love the environment and people, especially folks just in the throes trying to get ahead, have a knack for messing that up big time.
The World Bank has all sorts of programmes on poverty, and their web pages are worth a look for anyone with time. One major statistic they give: Something like 50 years, Asia had most of the world's poor; by 2050, Africa will have thoroughly cornered that "market" (although South Asia might still be a "serious competitor"). Among the reasons given:
* Although African economies are growing---and quite rapidly relative to other regions---the population too keeps growing at rate that is too rapid for the absolute numbers of poor to decrease, even if the proportions are decreasing.
* Moreover, the fruits of all that economic growth is not getting spread around "evenly". [One of the bank's major themes these days, w.r.t. poor countries is "shared prosperity".]
* What it takes to lift masses out of poverty is now reasonably well-understood, but African countries are hardly doing it.
In relation to the third, take Our Beloved Country (one of the better-off places on the continent) as an example: What exactly is the government of Kenya doing or planning to do that will lift the masses out of poverty? I can't readily think of anything, but I keep hearing of little jokes like Ajira Digital: hundreds of thousands will be put through 1-week training programmes, and they will then get busy in BPO. Seriously.
A rapidly-growing population is not necessarily bad and is probably even good---provided people can be put to real work. Africa has plenty of youthful and energetic people, with many more daily in the pipeline, but do they really have the opportunities to make a substantial contribution to economic development? Kenya is one of the better-off places in Africa. But on any day take a look at the number of youthful "idlers" in the towns, cities, and rural shopping centres.
In Europe, I imagine that people are concerned with these youthful "idlers" getting desperate enough to do the Mediterranean thing. The numbers keep growing, so that even if only 1% make it ... and the 1% men---burly types who can row across the sea in a dinghy---get to do "things" to nice, little blonde girls!
Macron of course got what he was "asking for", with his talk of "civilizational problems" and "seven or eight children". Past that, he had other interesting remarks:
***What if he'd said four or five?