Pākehā fertility was high in the 19th century because most women married at young ages. Fertility peaked in the 1870s, then dropped significantly as more women delayed marriage or did not marry at all. The fertility rate increased rapidly in the 1940s. This resulted in the 'baby boom', which lasted until the early 1970s. The increasing availability of a range of contraceptives from this period led to another substantial decline in total fertility rates (all ethnic groups combined), which dipped below replacement level (2.1 births per women) in the 1980s, 1990s and early 21st century. In 2017 it was around 1.8 births per woman, the lowest experienced in New Zealand.