In late-stage capitalism there are many structural forces against population growth. I think we will see population decline significantly in the next 20 years.

Women having access to healthcare and contraception is one structural force. Cell phones and the internet where women can find information easily is another. Media showing women having fulfilling lives not being mothers is another. The biggest issue is women being forced to work outside the home and having no help with child rearing. This puts and economic strain on families not to have children.

Capitalism values work and workers. 'Women's work' is not valued under current capitalist (and socialist) regimes. Women who take time off to raise children don't pay into retirement, and can't retire in many countries.

I think you will see a declining birth rate similar to Japan, and countries trying all sorts of coercion to get women to have more children.