Source:
https://scmp.com/article/999372/family-planningFamily planning
In the 21st century, low fertility and its impact on slowing population growth have become a great concern of governments in many parts of the developed world. A total fertility rate of 2.1 children per woman is regarded as the level of inter-generational replacement: a generation of women must each give birth to slightly more than two children to ensure replacement.
Hong Kong has one of the lowest total fertility rates in the world, at 1.04 per woman. The decline in fertility has been shown to be related to the substantial decrease in the proportion of married women of prime childbearing age.