Low fertility is a recent phenomenon in most developed economies. After the Second World War, the “baby boom” was considered a major challenge all over the world. During this period the importance of and need to limit population growth began to receive more public attention in Hong Kong, and discussions came to a peak at about the time of the World Population Year 1974, during which several local activities were sponsored by the Family Planning Association of Hong Kong (FPAHK). The high-priority issues mainly focused on the baby boom and the need for birth control, family planning, and limitations on family size. The large influx of immigrants from mainland China in the 1960s and 1970s was also a great concern. However, over the three decades since 1976, Hong Kong has experienced a rapid fall in fertility. The total fertility rate dropped steadily from the replacement level down to the lowest level in the world. An important challenge in Hong Kong today and in the near future is to curb falling fertility rates, which in the absence of migration will lead to a downward spiral in population size.