Childbearing for women born in different years, England and Wales: 2023

• In this bulletin, we focus on the fertility patterns of women born in 1978 and compare them with past and projected future generations; this is the most recent cohort for which we have observed completed family size data.

• Women in England and Wales who were born in 1978 have an average completed family size of 1.95 children, which is the highest average since women born in 1961; however, this is a lower average when compared with 2.04 children for their mothers' generation (assumed to be those born in 1951).

• Women born in 2007 (considered to be the daughters of those born in 1978) are projected to have smaller families than their mothers, with an average completed family size of 1.52 children; this estimate uses the 2022-based principal national population projections.

• Completed family size in England and Wales is projected to decline; baby girls born in 2025 are projected to have an average of 1.46 children throughout their life.

• The age at which women are having children is increasing, with women born in 1978 having on average one child per woman by age 31 years; for their mothers' generation (born in 1951), this occurred by age 26 years.

• Women born in 2007 (considered to be the daughters of those born in 1978) are projected to have an average of one child per woman by age 35 years; for those born in 2025, this is projected to occur by age 36 years.

Measuring family size

We calculate observed cohort fertility rates using birth registrations and female population estimates data. We present these rates by year of birth of the mother, rather than year of birth of the child. The observed fertility rates in this release use birth registration data up to 2023 to show fertility for different cohorts. Women born in 1978 are the most recent cohort for which completed family size is based entirely on observed data; they will have reached age 45 years in 2023.

Fertility rates using data from the 2022-based national population projections (NPPs) principal projection for England and Wales are also included in this release. They provide insights into possible future fertility for different cohorts of women that have not yet completed childbearing. They also show how completed family size could change in the future under specific demographic conditions.

Projections become increasingly uncertain the further they are carried forward. This is because of the inherent uncertainty of demographic behaviour. For example, there will be more certainty in projected completed family sizes for cohorts of women close to completing their childbearing, because these will be largely based on observed data, compared with the cohorts at the start of their childbearing years.

Completed family size

Completed family size is the average number of live-born children a group of women who share the same year of birth have had, or are projected to have, when assumed to have completed their childbearing.

Figure 1: Average completed family size is projected to decline

Past and projected average number of live-born children to women (completed family size), by year of birth of women, England and Wales, 1920 to 2032

Notes

1. The y-axis on this graph does not start at zero.

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Figure 1 shows that the completed family size for women born in 1978 was, on average, 1.95 children. This is the highest observed average completed family size since women born in 1961. The highest completed family size was recorded for women born in 1934 and 1935, with an average completed family size of 2.42 children.

There has been a slight increase in the average completed family size year-on-year since the lowest recorded value of 1.89 children for women born in 1972 and 1973. However, projected data suggests that we may see a decline in completed family size in the future. Baby girls born in 2025 are projected to have 1.46 children on average throughout their life.

Generations

This section compares the fertility of four different generations of women, including:

• the 1978 cohort, which is the latest to complete childbearing, with a completed family size of 1.95 children

• the 1951 cohort, which had a larger completed family size of 2.04 children; they are considered to be the mothers of the 1978 cohort 

• the 1923 cohort, which had a completed family size of 2.10 children; they are considered to be the grandmothers of the 1978 cohort and the mothers of the 1951 cohort

• the 2007 cohort, which are projected to have a lower average completed family size at 1.52; they are considered to be the daughters of the 1978 cohort, the granddaughters of the 1951 cohort, and the great-granddaughters of the 1923 cohort

These generations are based on the standardised mean (average) ages of women giving birth in 2007, 1978, and 1951.

Figure 2 shows the cumulative fertility patterns for the four different generations. For earlier cohorts, women had most of their children by the time they reached age 30 years; this was around two-thirds for women born in 1923 and three-quarters for women born in 1951. The 1978 cohort had around half their children by the age of 30 years, whereas women born in 2007 are projected to have most of their children (around two-thirds) after turning 30 years old.

Age at childbirth

The average age of women in England and Wales at childbirth (standardised mean age of a mother) was 30.9 years in 2023. This has generally been increasing since the mid-1970s.

In this section, we look at how age at childbirth changes over time for different cohorts of women. The age at which there is an average of one child per woman has been increasing over time as successive cohorts of women are having children at older ages. The point at which there was an average of at least one child per woman was by age 31 years for the cohort of women born in 1978. At this point, an average of 1.10 children per woman had been born. For their daughters’ cohort (born in 2007), this is projected to increase to age 35 years, where 1.05 children are projected to have been born per woman. For girls born in 2025, this is projected to increase to age 36 years.

Figure 3 shows that the 1923, 1951, and 1978 cohorts of women had similar completed family sizes of around two children per woman on average, despite having different fertility trajectories. Two-child families remain the most common completed family size, with 38% of women born in 1978 having two children. The proportion of women having no children has also remained fairly stable. This accounts for 16% of women in this cohort.

The more recent cohorts born in 2007 and 2025 are projected to have lower fertility at all ages, and smaller average completed family sizes. A baby girl born in 2025 is projected to have a completed family size of 1.46 children on average throughout her life. Information on the distribution of women by the number of children they have had is not available for projected cohorts.

Figure 4: Recent cohorts of women are projected to have higher fertility rates at older ages

Past and projected age-specific fertility rates at selected ages, by year of birth of women, England and Wales, 1920 to 2032

Notes:

1. These data are presented in completed years. Figures should be interpreted as the average number of children a group of women have had at a specific age. For example, figures for age 20 years represent live births to women age 20 years up to the day before their 21st birthday.

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Figure 4 includes selected age-specific fertility rates. It shows that the age at childbearing has increased over time for different cohorts of women.

Women born in 1951 had much higher fertility rates at age 25 years than age 35 years. For the 1978 cohort, fertility rates were similar at age 25 years and age 35 years.

Looking at changes between the 1978 cohort and the projected rates for their daughters (born in 2007), women in the 1978 cohort had a fertility rate at age 20 years that was more than double than that at age 40 years. However, the opposite is projected to be the case for their daughters. 

Births

In this bulletin, the number of children is based solely on the number of live-born children a woman has had. Stillbirths, adopted, fostered, or stepchildren are not included because the statistics are based on live birth registration data. 

Cohort

A cohort is a group of women with the same year of birth. 

Completed childbearing

For this bulletin, we look at women between the ages of 15 and 45 years. This is because the number of women who have children before the age of 15 years and after the age of 45 years are small and do not affect the overall patterns. Births to younger women are included at age 15 years. Births to women aged 46 years and over are included by using a proxy based on the number of births to women aged 46 years and over born in previous years. 

Completed family size

The average number of live-born children for women who are assumed to have completed their childbearing.

Our final "completed family size" rates for the 1978 cohort include births to mothers aged 45 years in 2023. It also includes births in 2023 to mothers aged 46 years and over for women who were born in earlier years. This means that births to mothers aged 46 years and over in earlier cohorts are used as a proxy for births that could occur to women aged 46 years and over in the 1978 cohort. Births to mothers aged 46 years and over remain a small proportion of total births. We use these final rates to refer to the completed family size of the latest cohort in this bulletin.

Completed age

The ages of women are presented in Figure 4 as "completed years". Therefore, fertility rates should be interpreted as the number of live births per 1,000 women by their age at their last birthday. For example, rates for those women aged 40 will include births up to the day before their 41st birthday. 

Exact age

The ages of women are generally presented in this bulletin as 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 40 years includes cumulative fertility through a woman's lifetime, up to the day before her 40th birthday.

Standardised mean age

The standardised mean (average) age is a measure that eliminates the effect of any changes in the distribution of the population by age. This enables analysis of trends over time. Standardised means are calculated using rates per 1,000 female population, by single year of age of mother. 

Further definitions are available in Section 11: Glossary of our User guide to birth statistics methodology.

Our Childbearing for women born in different years, England and Wales Quality and Methodology Information (QMI) provides information on strengths, limitations, appropriate uses, and how the data were created. 

Birth statistics are derived from information recorded when live births and stillbirths are registered in England and Wales. 

In this bulletin, the number of children is based solely on the number of live-born children a woman has had. Stillbirths, adopted, fostered or stepchildren are excluded.

For this bulletin, we look at women between the ages of 15 and 45 years. A small number of women complete their childbearing after this, but these do not affect the overall patterns. Births to women aged 46 years and older are included by using a proxy based on the number of births to woman aged 46 years and older in previous cohorts. 

We published population estimates for mid-2023 for England and Wales in July 2024, along with revised mid-2022 population estimates for England and Wales. Changes to the 2022 mid-year estimates, which are used to calculate fertility rates in the childbearing data, resulted in no differences to the 2022 rates previously published in our Childbearing for women born in different years, England and Wales: 2021 and 2022 bulletin. For more information on revisions to the mid-year population estimates, please see our Mid-year population estimates QMI.

This release contains projected data from our 2022-based national population projections (NPPs). NPPs are not forecasts, and they do not predict the effect of future government policies, changing economic circumstances, or other factors on demographic behaviour like fertility patterns. NPPs reflect what could happen under a particular set of assumptions, based on past trends and expert opinion. Several variant population projections are available, which provide a range of future scenarios based on alternative assumptions of future fertility, mortality and migration. We only present the principal assumptions in this release.

This bulletin presents statistics on childbearing among women in England and Wales by the year of birth of the mother. The year is approximate, and based on calendar year of occurrence and age of mother at childbirth. For instance, women aged 32 years giving birth in 2012 could have been born in 1979 or 1980; they are counted in the 1980 cohort. 

Male cohort fertility rates are not available because the same data are not collected at the birth registration as they are for women. Current registrations do not collect data on the number of previous children a man has had. This prevents the calculation of the proportion of men who have not fathered a child. A man's reproductive span is not as well-defined, so would also need a longer time series to calculate cohort measures. More information about male period fertility rates is available in our Birth characteristics in England and Wales bulletins. 

Our User guide to birth statistics provides further information on data quality, legislation, and conceptual procedures.

Accredited official statistics

These accredited official statistics were independently reviewed by the Office for Statistics Regulation in September 2011. They comply with the standards of trustworthiness, quality and value in the Code of Practice for Statistics and should be labelled "accredited official statistics.