Cohort Fertility: 2012

• The average completed family size for women born in 1967 and reaching age 45 in 2012, was 1.91 children per woman. This compares with their mothers’ generation, represented by women born in 1940, who had on average 2.36 children

• Two children was the most common family size for women born in both 1940 and 1967

• The level of childlessness among women born in 1967 (19%) is higher than for women born in 1940 (11%). One in ten women born in 1967 had four or more children, compared with nearly one in five women born in 1940

• Women born in 1982 have had slightly fewer children on average (1.02) by their 30th birthday than women born in 1967 who had 1.16 children by the same age

This bulletin presents statistics on childbearing among women in England and Wales. These figures are presented by the year of birth of mother – for ‘cohorts’ of women born in the same year - rather than by the year of birth of child. The estimates have been updated with 2012 births, the latest data available, which means that completed family size for women born in 1967 (women reaching age 45 in 2012) is presented for the first time.

This statistical bulletin provides supporting commentary for the cohort fertility package which includes data tables on:

• average number of live-born children, age and year of birth of woman, 1920-1997

• proportion of women who have had at least one live birth, age and year of birth of woman, 1920-1997

• percentage distribution of women of childbearing age by number of live-born children, age and year of birth of woman, 1920-1993

• age-specific fertility rates, age and year of birth of woman, 1920-1997

Table A shows the average family size and estimated family size distribution for women who have completed their childbearing years in 2012, and of the cohort assumed to be their mothers. The 1940 cohort is assumed to be their mothers' generation because the average age of mothers giving birth in 1967 was 27 years, and women of that age were born in 1940.

This comparison of the most recent cohort to have finished their childbearing with their mothers' cohort lets us examine change over time. The completed family size of the 1967 cohort is much smaller than for the 1940 cohort, and the proportion of women remaining childless is substantially higher for the 1967 cohort.

A cohort is a group of women born in the same year. Cohort fertility analyses explore whether current generations of women of childbearing age are reaching, exceeding or falling short of the fertility levels of previous generations. This bulletin contains statistics on changes in average family size and past and present levels of childlessness for different cohorts of women, and the proportions of women having one, two or more children.

The key cohort presented here is women born in 1967, who were aged 45 in 2012. This is the most recent cohort that is assumed to have completed their childbearing (see note 1). This statistical bulletin compares the completed family size of women born in 1967 with that of their mothers’ generation; the average age of mothers giving birth in 1967 was 27 years, and women of that age were born in 1940.

Women born in 1982, who have reached age 30 in 2012, are also used as a comparison group, as age 30 (see note 2) may be considered the mid-point of childbearing age. This bulletin compares the achieved fertility of the 1982 cohort by this age with that of previous cohorts by the same age.

Notes for what is cohort fertility?

1. A woman is assumed to have completed her childbearing by the last day she is aged 45, that is by her 46th birthday (exact age 46). Completed fertility includes fertility rates up to and including age 45. See background note 4 for a more technical explanation.

2. The ages of women are presented in 'exact years'. Therefore figures should be interpreted as the average number of children a woman has had up to that birthday. So childbearing up to exact age 30 includes cumulative fertility through her lifetime up to the day before her 30th birthday. Any childbearing in the 12 months from her 29th birthday onwards will be included in fertility up to exact age 30. See background note 4 for a more technical explanation.

The average number of live-born children a woman has had by the end of her childbearing years (completed family size) has been falling but has stabilised for recent cohorts (Figure 1). Women born in 1967 had on average 1.91 live-born children, which remains unchanged from the 1966 cohort. This compares with women born in the 1930s and 1940s, who had on average between 2.1 and 2.4 children. Cohorts of women born from 1958 onwards have had on average fewer than two children per woman. This decrease in the average family size is mainly due to rising levels of childlessness, which is discussed further in the next section.

Figure 1: Average number of live-born children by age 30 and completed family size, by year of birth of woman

England and Wales

Notes:

Table 1 in the cohort fertility release and Figure 1 measure cumulative fertility. For example, Figure 1 shows that women born in 1981 had given birth to 1.01 children on average up to their 30th birthday (this includes fertility up to and including age 29).

Download this image Figure 1: Average number of live-born children by age 30 and completed family size, by year of birth of woman

.png (114.9 kB) .xls (59.4 kB)

The average number of children women have had up to their 30th birthday can give an indication of more recent trends in family size. Figure 1 shows a slight upturn in average family size by the 30th birthday for the most recent cohorts, from 0.99 children for the 1975 cohort to 1.02 for the 1982 cohort. This is mainly because women born in 1982 had higher fertility rates in their late twenties than those born in 1975. There is no single explanation for this increase, but possible reasons include the changes in support for families introduced by the previous government (such as tax credits and maternity/paternity leave), and the increasing proportion of women aged 25-29 who were born outside the UK (with fertility above the UK born average) (See section note 1).

The average number of children women have had up to their 30th birthday can give an indication of more recent trends in family size. The 1967 cohort had 1.16 children on average by their 30th birthday, compared with 1.89 by the same age for their mother’s generation, the 1940 cohort. Overall, women born in the 1960s and 1970s have had fewer children by age 30 than previous generations. This reflects their postponement of childbearing to older ages, for reasons including:

• increased participation in higher education (see section note 2)
• delayed marriage and partnership formation, and
• the desire to establish a career, get on the housing ladder and ensure financial stability before starting a family (see section note 3).

Notes for average family size

1. For a detailed analysis of childbearing among UK and non-UK born women see this ONS report.
2. Ní Bhrolcháin, et al., 2012
3. Jefferies, 2008 (297 Kb Pdf) (297 Kb Pdf)

Childlessness is estimated as the proportion of women who have not had a live birth by a specific age.

Figure 2: Percentage of women remaining childless(1) by their 30th birthday and completion of childbearing, by year of birth of woman

England and Wales

Source: Office for National Statistics

Notes:

1. The percentage of women remaining childless by age 30 and by completion of childbearing is calculated as 1 minus the proportion of women who have had at least one live birth by that age, multiplied by 100
2. This calculation takes into account all first live births from a woman's teenage years through to the last day she is 29 (the day before her 30th birthday) or the last day she is 45 (the day before her 46th birthday)

Download this image Figure 2: Percentage of women remaining childless(1) by their 30th birthday and completion of childbearing, by year of birth of woman

.png (17.7 kB) .xls (55.8 kB)

Figure 2 shows that the level of childlessness for women reaching age 45 born in 1967, is high at 19%, but slightly lower than for the previous six cohorts, of whom 20% remained childless. Around one in five women born in 1967 (and 1920) remained childless by the end of their childbearing years compared with one in nine women born in 1940. A wide range of explanations relating to circumstances and choices have been put forward for the increasing childlessness seen in recent cohorts. These include the decline in the proportion of women married, changes in the perceived costs and benefits of childrearing versus work and leisure activities, greater social acceptability of the childfree lifestyle and the postponement of decisions about whether to have children until it may be biologically too late (see note 1).

On their 30th birthday, 45% of the 1982 cohort were childless, a slightly higher proportion than for the 1967 cohort at the same age (42%). This highlights the trend that women have been increasingly delaying having children to older ages. However, Figure 2 shows that the proportion of women childless by age 30 has been falling for successive cohorts born from 1975 onwards. 48% of women born in 1975 had not had a live birth by age 30. This suggests a slight reversal and reflects the higher levels of childbearing among women in their late twenties born in 1982 compared with those born five years earlier.

Notes for childlessness

1. For reasons for increasing childlessness, see for example:

   O'Leary L, Natamba E, Jefferies J and Wilson, B (2010) Fertility and partnership status in the last two decades, Population Trends 140, page 5-35- (95.5 Kb Pdf)

   Simpson, R (2009) Delayed childbearing and childlessness in Britain, in Stillwell, J, Kneale, D and Coast, E (eds.) Fertility, Living Arrangements, Care and Mobility Understanding Population Trends and Processes Volume 1, Springer, Dordrecht, pp. 23-40.

   Kneale D, Joshi H (2008) Postponement and childlessness:Evidence from two British cohorts VOLUME 19, ARTICLE 58, (2008) http://www.demographic-research.org/Volumes/Vol19/58/

   Basten, S (2009). Voluntary childlessness and being Childfree. The Future of Human Reproduction: Working Paper #5.

   Berrington, A.M. (2004). Perpetual postponers? Women's, men's and couple's fertility intentions and subsequent fertility behaviour. Population Trends 117: 9-19. (137.7 Kb Pdf)

Figure 3 shows that the proportion of women who have had a live birth by age 20 has been gradually decreasing for more recent cohorts, from a peak of around two in ten for women born in 1952, to around one in ten women for those born in 1992, the most recent cohort to reach age 20. This shows that the proportion of women becoming teenage mothers is falling, though the level of teenage motherhood remains above that of the cohorts born in the early 1920s where around 7% of women had a child by age 20. This fall in the proportion of teenagers becoming mothers has accompanied recent falls in the annual number of teenage conceptions.

Conception statistics include all pregnancies of women usually resident in England and Wales which lead to either a live birth, still birth or an abortion under the 1967 Act. The conception rate for women aged under 20 fell by 20% over a decade to 48.9 conceptions per thousand women aged 15–19 in 2011 (from 60.8 in 2001). Teenage conception and birth rates are used widely as outcome indicators in the sexual health context (See note 1).

Notes for teenage childbearing

1. More details on teenage conceptions can be found in the annual ONS conceptions release.

The traditional two-child family remains the most common family type in England and Wales, with 37% of women born in 1967 having two children (Figure 4, Table B). Childlessness is the second most common family size for the 1967 cohort. This is a recent development first encountered among the 1964 cohort, whereas for those born between the late 1930s and early 1960s, three children was the second most common family size. A woman born in 1940 was more likely to have one, three or, ‘four or more’ children than not to have any. Only one in ten women born in 1967 had four or more children, compared with nearly one in five in the 1940 cohort (Table B).

The proportion of women with a one-child family has shown a slight increase for women born between 1940 and 1967 with 15 per cent of women born in 1967 having a one-child family. The proportion of women with only one child was highest for women born in the 1920s, where around one-fifth had one child – this may be because their marriage and childbearing were delayed or disrupted by World War II.

Looking at the fertility rates of selected cohorts at particular age milestones highlights how the age distribution of women giving birth has varied over time. As an example, the three vertical lines on Figure 5 allow a comparison of the age profile of fertility in the 1967 cohort, who have completed their childbearing, their mother's generation cohort of 1940 and that of the 1982 cohort to date.

For the 1967 cohort the highest fertility rate of those shown was at the age of 25, closely followed by age 30. Lower levels of fertility were recorded at the ages of 20 and 35, while the number of live births per 1,000 women at age 40 was lower still. On average the 1967 cohort had 1.91 children per woman. However, fertility levels at age 35 and 40 were higher in the 1967 cohort than in the 1940 cohort.

Age-specific fertility rates for the 1982 cohort are currently only available up to the age of 30. For this cohort, fertility rates at age 30 were higher than for the 1967 cohort and at a level last encountered by women born in the late 1930s. In contrast, fertility at age 20 for the 1982 cohort was slightly lower than seen for the 1967 cohort, and at the age of 25 it was much lower (88 births per 1,000 women aged 25 for the 1982 cohort compared to 111 for the 1967 cohort).

Fertility at age 25 hit a low for women born in 1977 before rising slightly among cohorts born between 1978 and 1985. Consequently, 25 year olds born in 1982 had 21% fewer live births per 1,000 women at this age than 25 year olds who were born in 1967.

If recent trends continue, the 1982 cohort would be expected to have an older average age at childbearing than the 1967 cohort.

• Characteristics of Mother 2 – this package presents live birth statistics (numbers and rates) within and outside marriage/civil partnership. It also provides data on first live births by marriage/civil partnership duration, and live births within marriage/civil partnership by age of mother and number of previous live-born children.

• Further Parental Characteristics – this package presents age-specific fertility rates for men, the average age of father, and paternities within and outside marriage/civil partnership. This package also presents data on birth registrations in England and Wales by National Statistics Socio-economic Classification (NS-SEC), where a household level classification is used taking the most advantaged NS-SEC in the household. More detail on this combined approach to NSSEC can be found on the ONS website (213.7 Kb Pdf) . These data were previously published as a separate package “Live Births by Socio-economic Status of Father, England and Wales”.

Key points from these releases

• The standardised mean age of father at birth of child has increased by nearly two years over the last two decades from 30.9 years in 1992 to 32.7 in 2012 (see background notes 6 and 7). The standardised mean age of mother increased by a similar amount over the same period, from 27.9 in 1992 to 29.8 in 2012.

• For men, the 30–34 age group had the highest fertility rate in 2012, the same age group that had the highest fertility rate for women. Previously, men in their mid-to-late twenties had the highest fertility rate but were overtaken in 1993 by men in their early thirties. The same trend occurred among women a decade later, with the fertility of women in their early thirties overtaking that of women in their mid-to-late twenties in 2004.

• In 2012, 36% of live births within marriage/civil partnership were first births, 38% were second births and 16% were third births.

• In 2012, households employed in intermediate and routine occupations had a mean age of mother under 30 years while households employed in higher managerial, administrative and professional occupations had a mean age of mother over 30 years.

The Office for National Statistics (ONS) uses birth statistics to:

• produce population estimates and population projections, both national and subnational

• quality assure census estimates

• report on social and demographic trends

Other key users of birth statistics include the Department of Health, academics, demographers, health researchers, lobby groups, international organisations and the media.

Cohort fertility statistics and estimates of fertility by family size are used by ONS for producing the fertility component of population projections and for reporting on social and demographic trends. They are also of key interest to academics researching changing family building patterns over time.

The Department for Work and Pensions uses information on family size for modelling future lone parents, pensions and benefits.

Estimates of childlessness are of interest to policymakers concerned with the support and care available to people at older ages. Estimates of family size are of use to special interest groups such as organisations and networks supporting large families and for people who are, or who have, an only child.