High birth rates, 1840 to 1870s
Between 1840 and the 1870s settler birth rates were high. At this time sexual intercourse mainly occurred within marriage. Because most women married, and did so at a young age, fertility was high. There were 6.5 to 7 live births per woman during this period – in 1878 there were almost 9 births per married woman. Māori fertility decreased at this time because of higher rates of miscarriage due to new communicable diseases like measles and whooping cough, the impact of malnutrition, and sexually transmitted diseases.
Declining birth rates, 1870s to 1930s
From the 1870s the Pākehā birth rate declined. It reached a low point in the 1930s during the economic depression, when it hovered around the population replacement level (2.1 births per woman). Women married later than in the mid-19th century, and more did not marry at all. Paid employment opportunities for women increased, and they often had to choose between work (and no children) or marriage (and children) – though some did both. Births outside marriage were still uncommon. These social changes led to lower birth rates and smaller family sizes: 2.9 children were born per woman in 1921, and 2.4 in 1931.
Birth control was limited. Though barrier methods such as condoms were available, married couples did not use them in significant numbers. Birth control became more significant later in the 20th century.
Māori fertility increased in this period as the effects of infectious diseases decreased. It remained at about six births per woman until the 1960s.
After the Second World War these trends reversed. In a return to the patterns of the mid-19th century, more women married and at younger ages – marriage remained a crucial factor influencing fertility rates. Women had their children young and in quick succession. These changes led to the ‘baby boom’ that lasted until the early 1970s. At its peak in 1961, the birth rate was 4.15 per woman.
The baby boom was mainly a Pākehā phenomenon. Māori women's fertility rates remained consistent from the 1930 until the 1960s, when there was a significant drop in the number of children per woman.
Boom turned to bust for Pākehā women by the early 1970s. By this time the contraceptive pill and sterilisation were commonly used to control fertility within and outside marriage. The link between marriage and fertility was severed as more women became mothers without being married. The birth rate dropped to a new low of 1.87 births per woman in 1983 before climbing to over two during the early 1990s as a large cohort of women who had postponed pregnancy started having children. The rate fluctuated around two per woman from this point on. While Māori fertility fell, the birth rate remained higher than for Pākehā because the overall Māori population was younger. Pacific peoples had a higher birth rate and also a younger population overall, resulting in a higher than average fertility rate.
New Zealand’s first surviving quadruplets were born in Dunedin in 1935. Bruce, Mary, Kathleen and Vera Johnson attracted public and media attention from the moment they were born. A large state house was provided for the family (which grew to eight in total) and became a tourist attraction. Behind the scenes the Johnsons struggled – mother Kathleen Johnson wrote in a letter to Prime Minister Michael Joseph Savage, ‘How different is our lives to what the public think … Two pocket handkerchiefs and 10/- from a sewing guild was their birthday presents last year.’1
Women over 30 are more likely to have multiple children than their younger counterparts. Delays in childbearing combined with fertility treatment led to a rise in the number of multiple births from the late 20th century. Between the 1880s and 1991, 9 to 11 live births per 1,000 confinements were twins (0.9–1.1%). In 2014 multiple births were 1.5% of all births and had been around this figure for a decade. This was a statistically significant increase and the proportion was higher than in some other Western countries, such as France.
Birth outside of marriage
Couples who conceived children outside marriage often got married before the birth – a trend which peaked during the post-Second World War baby-boom years. Adoption was a common outcome when marriage did not take place.
This changed over the last decades of the 20th century. In 1962, 8% of babies were born outside of marriage. The proportion increased to 23% in 1982 and 44% in 2002. By 2015 it was 47%. In many cases the parents who were living together and bringing up their children jointly, but were not formally married.