Meh, personally I think pollution impacts on fertility might be overblown. Not in any way negligible, just overrated.

For example, microplastics are being found everywhere now but widespread plastic use was about 1/6th the current levels over 40 years ago so you would expect it to have been an issue going back decades. Methane emissions also cause birth defects and loss of fertility, but states with refineries and flare stacks also have higher rates of teen mothers (unintuitive correlation of conservative policies).

On the other hand, the fastest growing populations are places such as the middle east with low to nonexistent women's rights, while the slowest growing are places with women in positions of power and education. In 1994 in Cairo the United Nations came up with a plan to curb poverty and starvation in the region by limiting population growth by... checks notes* educating women.

That all said: Population Decline is a good thing. It should decline. 200 years ago we had a billion people, and we had flourishing arts and sciences and engineering marvels such as the London Underground, typewriters, trains and canals across continents, the first Soda Fountain. Less people doesn't hinder humanity in any feasible way. More people is going to kill this planet.

Sorry for the rant.