It will probably take about 100 years to reach population equilibrium on Earth, and then only if we consciously seek it, starting now. "Mother" starts the discussion by pointing out, first, that we have a very serious problem, and then through the voices of experts and visionaries Mother tells us what will happen if we don't address the problem. Then the movie focuses our attention on the one and only way to peacefully and painlessly decrease the population -- through family planning. And family planning requires female empowerment. The movie tears away the curtain of despair and denial, eschews violent and unethical reactions, avoids placing the blame, and shows us how to navigate though these uncertain times by empowering women.
I wish I could see a sequel. It would cover the technology of contraception, the demographic pyramid, and the belief systems that stand in the way of controlling our reproduction rate. To answer the question of the previous reviewer, yes, zero population growth could be attained today if no pregnancies were unplanned.