This is a cumulative probability market. For an answer to resolve YES, reports/publications/data from any sufficiently conventionally high-status source (e.g. the UN Population Division, the World Bank, the CIA World Factbook, the Population Reference Bureau) need to come out before the date of that answer claiming that the world's Total Fertility Rate is at or below 2.1 (replacement level can change depending on mortality rates, sex ratio, etc. but 2.1 is the figure for the purposes of this question).

Not that publications after an answer's date that make this claim are not eligible to count towards this question, even if they concern time periods before the date in question. The actual claim itself that humanity has fallen below replacement level needs to be made before the year in the answer in question.

I will use my discretion on what sources I will count, but expect it to be conservative. Feel free to ask about sources ahead of time.