Childbearing for women born in different years, England and Wales: 2018

• The average completed family size for women in England and Wales who reached age 45 years in 2018 (having been born in 1973) was 1.89 children per woman, unchanged from the previous cohort (women born in 1972); this is the lowest level since the series began.

• The proportion of women having just one child has risen in recent cohorts completing their childbearing (from 14% for women born in 1946 to 18% for women born in 1973), but two-children families remain the most common family size (37% for women born in 1973).

• Of the women who reached age 45 years in 2018, 19% were childless at the end of their childbearing years; this is more than double the proportion of childlessness (9%) in their mothers' generation born in 1946 but is similar to levels seen for women born since the late 1950s.

• The most common age at childbirth for women born in 1973 was 31 years, compared with 24 years a generation before (women born in 1946).

• By age 30 years, 53% of women born in 1973 had at least one child, compared with 82% for their mothers' generation.

This release presents statistics on childbearing among women in England and Wales by the year of birth of the mother, rather than the year of birth of the child. A group of women with the same year of birth are referred to as a “cohort” throughout.

“Cohort fertility” analyses compare the fertility levels of current generations of women of childbearing age with previous generations. This covers changes in average family size, levels of childlessness and the proportions of women having one, two or more children.

In this release, the number of children is based solely on the number of live-born children a woman has had. Stillbirths and any adopted, fostered or step-children are excluded from the number of children a woman has.

Completed family size is the average number of live-born children for women who are assumed to have completed their childbearing.

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

A woman’s childbearing is assumed to start at age 15 years and end at age 45 years (the day before her 46th birthday). The estimates have been updated with 2018 births, which means that completed family size for women born in 1973 (women reaching age 45 years in 2018) is presented for the first time. Women born in 1988, who reached age 30 years in 2018, are also used as a comparison group, as age 30 years may be considered the mid-point of a woman’s childbearing years.

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. Childbearing up to exact age 30 years includes cumulative fertility through a woman’s lifetime up to the day before her 30th birthday. Any childbearing in the 12 months from her 29th birthday onwards to the day before her 30th birthday will be included in fertility up to exact age 30 years.

Women born in 1973 (the most recent cohort to complete their childbearing in 2018) had on average 1.89 children (Figure 1), unchanged from the previous cohort (women born in 1972). This is the second consecutive year the completed family size has been 1.89 children per woman. In comparison, women born in 1946 had an average completed family size of 2.19 children per woman. Women born in 1946 are assumed to be the generation of mothers of the women born in 1973 based on the average age of mothers at childbirth in 1973 being 27 years.

The average number of live-born children that women have by their 30th birthday gives an indication of more recent trends in family size (Figure 1). Although, as women delay childbearing to older ages, the number of live-born children a woman may have by her 30th birthday will become less indicative of trends in family size.

The average number of children by age 30 years has fallen from a peak of 1.89 children for women born in 1940 to just one child per woman (1.00) for women born in 1973.

Figure 2 shows how the average completed family size for women born in 1973 (1.89 children per woman) and their mothers’ generation born in 1946 (2.19 children per woman) is distributed by the number of live-born children. It is clear to see that a lower percentage of women born in 1973 had two or more children than women born in 1946, whereas a higher proportion had just one child or remained childless by the end of their childbearing years.

Increasing childlessness in recent cohorts may be because of a decline in the proportion of women married; changes in the perceived costs and benefits of child-rearing versus work and leisure activities; greater social acceptability of a childfree lifestyle; and the postponement of decisions about whether to have children until it may be biologically too late.¹

Compared with some other countries, England and Wales has seen high levels of childlessness over the past 20 to 30 years. For cohorts born between 1960 and 1970, on average over this decade, England and Wales had one of the highest percentages of childlessness following completion of childbearing.²

Figure 3 shows changes in family size over time between the 1920 and 1973 cohorts. Two-children families continue to be the most common family size, including for women born in both 1973 and 1946 (also shown in Figure 2). After peaking around 1950, with 44% of women having two children, it stabilised at 38% for cohorts born through the 1960s before declining slightly to 37% for the 1967 to 1973 cohorts.

The reduction in large family sizes (those including four or more children) and the increase in the proportion of childless women can also be clearly noted when looking at Figure 3 for the post-War generations.

Notes for Women are having smaller families than previous generations, but two-children families remain the most common family size

1. For reasons for increasing childlessness, see articles: Fertility and partnership status in the last two decades; Postponement and childlessness: Evidence from two British cohorts (PDF 279.15KB); and Childlessness in the UK.
2. Human Fertility Project - The Human Fertility Database

As well as the average number of children women have by age 30 years having fallen (Figure 1), the proportion of women who reached their 30th birthday without having given birth has changed substantially over time (Figure 4). Nearly half (48%) of women born in 1988 (the most recent cohort to reach age 30 years) were childless, compared with 37% for their mothers’ (1960 cohort) and 25% for their grandmothers’ (1932 cohort) generations by their 30th birthday.

The lowest levels of childlessness at age 30 years occurred for women born in the early 1940s where on average just 18% of women had not given birth by age 30 years, less than half of the 1988 cohort level.

Figure 4 also shows that despite an increasing trend in childlessness in recent years by age 30 years, the percentage of women who are childless by the end of their childbearing years has remained fairly constant for women born since the late 1950s. This suggests that women are delaying childbearing rather than not having children.

The most common age at childbirth for women born in 1973 who reached age 45 years in 2018 was 31 years, an increase compared with 24 years for their mothers’ generation born in 1946. Figure 5 shows the ages of women giving birth for each of the selected cohorts.

The 1925, 1935 and 1946 cohorts show the highest number of births per thousand women were occurring when women were in their early to mid-20s. By the 1955 and 1965 cohorts, the peak age at which women were having children was in their mid-to-late 20s. By the 1973 cohort and 1985 cohort, who have yet to complete their childbearing years, the highest number of live births per thousand women occurred when women were in their early 30s. This is evidence that women are tending to delay their childbearing. The most recent cohort visible on the chart (women born in 1995) is so far displaying a "flatter" trend, showing the recent decrease in births to teenage mothers.

It is also noticeable that for the cohorts from 1965 onwards, the curves have "flattened" out. This suggests that as well as delaying, women are also tending to spread births more over their childbearing lifetime than previous cohorts.

Some of the reasons for women delaying childbearing may include:

• greater participation in higher education

• delaying marriage and/or partnership formation

• wanting to have a longer working career before starting a family

• labour market uncertainty and the threat of unemployment

Annual summary birth statistics for the UK and its constituent countries, including international comparisons of live birth rates, can be found in the Vital statistics in the UK: births, deaths and marriages.

More details on teenage conceptions can be found in Quarterly conceptions to women aged under 18 years and the annual conceptions release.

For information on data quality, legislation and procedures relating to birth statistics, please see the User guide for birth statistics.

This release was previously called "Cohort Fertility" and was renamed as "Childbearing for women born in different years" in 2013.

The Births Quality and Methodology Information (QMI) report contains important information on:

• strengths and limitations of the data and how it compares with related data

• the uses and users of the data

• how the output was created

• the quality of the output: including the accuracy of the data

During May 2012, changes were made to the Population (Statistics) Act 1938, which means that information on the number of previous children and whether previously married is now collected from all mothers at birth registration and not just from married women. This change highlighted an issue with the number of previous children being reported at birth registration, which the Office for National Statistics (ONS) noted at the time (PDF, 539KB).

In January 2016, an improvement was made to the registration system to rectify this issue.  

Further amendments have been made to the wording of the question surrounding previous children asked at birth registration. The most recent paper we published on the previous children issue is available.

The methods used to create cohort fertility require use of data collected at birth registration from women on the number of previous children they have had. At present, the birth registration system does not collect information on the number of previous children a man has had. Without this information, it is not possible to produce estimates of the proportion of men who have not fathered a child.

It is also important to note that a man's reproductive span is not as well-defined as a woman's, in terms of the upper age at which a man can father a child, and so this means we would need a longer time series to calculate cohort measures. Male period fertility rates can be found in Births characteristics in England and Wales.

The revisions policies for population statistics are available.

Further information on the data sources and methods for producing this output can be found in the metadata tab of the data tables.

National Records of Scotland provides more detailed birth statistics for Scotland, including cumulative fertility by cohort.

The Northern Ireland Statistics and Research Agency provides more detailed birth statistics for Northern Ireland, including cumulative fertility by cohort.

Special extracts and tabulations of births data for England and Wales are available to order for a charge (subject to legal frameworks, disclosure control, resources and agreement of costs, where appropriate). Such enquiries should be made to Vital Statistics Outputs Branch via email at vsob@ons.gov.uk or telephone on +44 (0)1329 444 110.

Enquiries on Childbearing for women born in different years, England and Wales, should be made to the Demographic Analysis Unit via email at pop.info@ons.gov.uk or telephone on +44 (0)1329 444 661.