I genuinely do not see the point you’re trying to make. Is it that pollution == lower birth rate? I’d imagine there are many factors besides pollution that may influence why certain regions have more birth rates than others.
The places with high birth rates are economically undeveloped, so the people there consume very few resources, produce very little pollution and have negligible impact on the environment. One person in the US produces the same amount of CO2 as 150 people in DR Congo. That disparity is broadly similar for metrics like land use, water use, soil depletion, waste production etc.
The number of people being born in very poor countries is essentially irrelevant compared to the consumption choices of people in rich countries. Based on current trends, the global population is expected to peak at around 10 billion, but the planet is comfortably capable of sustaining billions more if we can find a middle ground in resource use between the dire poverty of DR Congo and the wanton profligacy of the US. Talking about birth rates in relation to climate change is at best a misguided distraction and at worst wilful misdirection.
We don't expect or desire (or IMHO even consider it acceptable) for these places to stay poor - the less developed countries on average have had steady improvements, a major reduction in poverty and the associated increase in consumption. The growth in emissions of China are not caused by some population growth but by the increase in prosperity of Chinese people, and we'd also expect places like DR Congo to steadily grow their consumption-per-capita.
The US currently has what was once the Earth's entire population. Much of the population can be explained by a steady flow of relatively poor immigrants.
The people in the high population growth rate regions aren't going to stay there, and their emissions will look similar to the nations they move to.
https://ourworldindata.org/grapher/children-per-woman-un
https://ourworldindata.org/grapher/co-emissions-per-capita