Okay the argument is that the lack of social safety nets and childcare causes a decline in birth rates. Right?

Your argument is that the transition from socialism to capitalism is directly linked to a drop in birth rates? I assume in this particular case you mean the loss of free childcare and social safety nets leads women to avoid having children?

So, in capitalist countries where there is subsidised/ free childcare and more developed safety nets should correspond to an increase in birth rates?

And to expand on that, socialist countries such as China and Cuba should show an increase in birth rates. An i getting this right or am I missing your point