The Cambridge Group for the History of Population and Social StructureAlice Reid
Today most of the world’s population lives in places where, on average, women have fewer than two children over their lifetime, but this level of childbearing is a relatively recent phenomenon.
Before the demographic transition – the change from high and variable birth and death rates to low birth and death rates (usually taken as 1870-1930 in the UK) – women had higher numbers of children, and it is generally accepted that they did not deliberately restrict the numbers of children they had.
Given that before the demographic transition in other parts of the world, women had an average of around six or seven children, it is surprising that British women have never had more than five children, on average, over the course of their lifetime.
Sir Thomas Remington of Lund in the East Riding of the County of York, Knight, Dame Hannah his wife, daughter of Sir William Gee of Bishop Burton, Knight, and their issue. 1647. Image courtesy of York Museums Trust. Public Domain.
How high is high fertility?
Theoretically a woman could fit in over 30 children during a roughly 30-year reproductive period between menarche and menopause. Although there are instances of individual women having between 20 and 30 children – for example Sir Thomas and Lady Remmington of Lund in Yorkshire, illustrated in the image above with their 20 children – this is very unusual, and there are very few societies, past or present, where the average number of children per woman exceeds eight. The highest documented fertility of any community is associated with the Hutterites, a small North American religious sect, where in the mid-20th century women had an average of 8.9 children.
There are a number of physiological and behavioural factors which can reduce the number of children born to each woman. These include miscarriage and stillbirth (which are generally not included in calculations of birth rates); the fact that some women lose the ability to conceive earlier than average through birth complications, disease, or early menopause; the fact that new mothers generally do not ovulate for some months after the birth of a child, and the longer and more intensively they breastfeed, the longer it takes for ovulation to return; and the fact that if the timing of sexual intercourse is random, couples might miss their fertile window in some months.
These factors together tend to reduce the number of children an average woman might have even if she was in a sexual relationship throughout her childbearing years, and not using any form of contraception, to around eight children.
Marriage patterns reduced fertility in historic Britain
Time spent outside sexual relationships reduces fertility still further in populations where no or few couples were trying to prevent conception, and this is the major factor reducing fertility levels in historic Britain. Before the demographic transition, when mortality was still relatively high, the death of either a woman or her husband would curtail her opportunity to have children.
More important for reducing numbers of children born in England and Wales to levels lower than many other parts of the world, however, were late ages at marriage and substantial proportions of women who never married.
Although sexual intercourse outside marriage did happen in the British past, most children were born to married couples until well into the last quarter of the 20th century (watch out for future blogs on this topic).
Photo from E. W. Hope, Report on the physical welfare of mothers and children (Liverpool, The Carnegie United Kingdom Trust, 1917), volume 1.
Both late ages at marriage and a substantial portion of the population who never married have the ability to considerably reduce the number of children born to a woman. We saw in a previous blog that the age of first marriage in England ranged between 24 and 26 until the post-2WW marriage boom, when women married younger than ever before. Given that the chance of conceiving reduces with age, particularly beyond the age of 30 or so, relatively late age at marriage means that women spent many of the most fertile years of their life unmarried and therefore with little chance of becoming pregnant.
In addition, a relatively high percentage of women (on average 13.5 percent) remained unmarried throughout their childbearing lives. When age at marriage was higher, more women never married at all, with as many of 27 percent of women born in the mid–17th century remaining single at age 50. There were very few time periods when less than five percent of women remained unmarried, and this occurred when age at marriage was low, for example among women born in the mid– 18th century.
In contrast in most South Asian countries (e.g. India, Bangladesh, Nepal, Pakistan) until the 1980s women married before age 20 and only one or two percent remained unmarried at age 50. These differences in marriage patterns are the main reason for considerably higher average numbers of children per woman before the demographic transition in South Asia than in Britain (and other parts of North-West Europe where marriage patterns were similar).
Fertility levels and population growth
Populations grow when there are more births than deaths (not counting the influence of migration). The relationship between fertility in terms of the number of children per woman and the number of births per 1,000 people is not a simple one, as it also depends on the age structure of the population. High fertility in the recent past can produce large cohorts of women in the childbearing ages, and these can contribute to a high number of births in relation to deaths even if the number of children each woman has is low.
Nevertheless, there is a widely used measure – the ‘replacement rate’ – that indicates the number of children a woman needs to have to ‘replace herself’ and therefore keep the population from either growing or shrinking. Globally, today, this number is around 2.1; just over two because although around half of all children born are female, slightly more children born are male, and also because not all children reach adulthood.
In the past, however, this number was considerably higher, principally because mortality was higher, so more children needed to be born in order to ensure that one female born survived to childbearing age. Therefore although women had between four and five children each in Britain, this did not mean the population grew rapidly. For most of the pre-industrial period, the British population grew slowly, if at all, because fertility and mortality were more or less in balance.
Unknown artist, Five Children of the Pigott Family (1740). Courtesy York Museums Trust.
Moderate fertility as part of a low-pressure regime
In other pre-demographic transition populations with low population growth, higher fertility levels were accompanied by higher mortality levels. When Tony Wrigley and Roger Schofield at Campop produced the long-run series of fertility and mortality for England, they suggested that this was part of a ‘low–pressure’ demographic regime. Such a regime was characterised by moderate levels of both fertility and mortality, with low fertility achieved through marriage as described above. In contrast, ‘high–pressure’ regimes were characterised by higher levels of both fertility and mortality.
How do we know?
Fertility, or birth rates, can be measured in a number of different ways. The simplest measure is the crude birth rate, the number of births in the population in a year, per 1000 people. This is easy to calculate, particularly since the state started to register births (1837 in England and Wales and 1855 in Scotland).
However, this blog has talked mainly about a different measure, the total fertility rate, which is defined as the number of children each woman could expect to have over the course of her childbearing life. We can measure this for actual cohorts of women (women born in particular years) by waiting until they reach the age of around 50, when further childbearing is unlikely, and counting the numbers of their children.
However, this means it is necessary to wait until a cohort has reached the age of 50, as it is not possible to derive this information from birth certificates. Instead most total fertility rates are ‘period’ rates, calculated by calculating fertility rates for age groups of women (numbers of children born to women in a particular age group and dividing by the number of women) and assuming that women go through their childbearing life experiencing those rates in sequence.
Period total fertility rates can be calculated for England and Wales since 1938, when the age of the mother started to be recorded on birth certificates. Between 1851 and 1938 they have to be estimated. Here we have estimated them from census data by working out the age at childbirth of women living with their children and making various adjustments for children who died or were not living with their mother (this technique is called the ‘own children method’).
For the pre-industrial period, total fertility can be estimated from parish registers which recorded baptisms, marriages and burials. Linking the births to different women, and to her own baptism, allows age–specific fertility rates to be constructed, and the numbers of births to women across their lives can be counted.
Photograph taken 1900 © Reproduced by permission of Oxfordshire County Council
Further reading
Bongaarts, J. (1975) Why High Birth Rates Are So Low. Population and Development Review, 1(2): 289-296.
Wrigley, E.A. and R.S. Schofield (1989) The Population History of England 1541-1871. CUP.
