Fertility for those born in different years, England and Wales: 2024

• Women born in 1979 (the most recent cohort for which we have completed family size) had an average completed family size of 1.95 in 2024; men born in 1979 have a lower average family size of 1.82 at this point in their life (by 45 years of age).

• Completed family size in England and Wales is projected to decline; women born in 2008 (considered to be the daughters of those born in 1979) are projected to have smaller families than their mothers, with an average completed family size of 1.48 children, while a baby girl born in 2026 is projected to have an average completed family size of 1.43.

• The proportion of women born in 1979 who have not had children is 15.7%, which is similar to their mothers' (14.8%) and grandmothers' (16.8%) cohorts.

• The age at which women are having children is increasing; for the 1979-born cohort of women, there was an average of one child per woman by 31 years of age, compared with 27 years for the mother's generation and 28 years for the grandmother's generation.

• The 1979-born cohort of men had an average of one child per man by 33 years of age, which is older than women born in the same year.

• Men born in 1959 (the latest cohort for which we have completed family size) had an average completed family size of 2.00 in 2024; this compares with a completed family size of 1.98 for women born the same year.

This release was previously called "Childbearing for women born in different years". It has now been renamed "Fertility for those born in different years".

Measuring family size

We calculate observed cohort fertility rates using birth registrations and female or male population estimates data. We present these rates by year of birth of the mother/father, rather than year of birth of the child. The observed fertility rates in this release use birth registration data up to 2024 to show fertility for different cohorts.

Women born in 1979 are the most recent cohort for which completed family size is based entirely on observed data; they will have reached 45 years of age in 2024.

For the first time, we have included cohort fertility data for men. As the upper age range of male fertility is less well defined, we have included age-specific fertility rates up to 65 years of age. This means that the latest cohort of men for whom we have completed family size data were born in 1959. Digital data from before 1964 are unavailable, so we are unable to show complete data for men born before 1949.

We have also included fertility rates for women using data from the 2024-based national population projections (NPPs) principal projection for England and Wales in this release. The NPPs provide insights into possible future fertility for different cohorts of women. They also show how completed family size could change in the future under specific demographic conditions. Projected data for men are not available.

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 projections will be largely based on observed data, compared with the cohorts at the start of their childbearing years.

Completed family size through the generations

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

Figure 1: Average completed family size is generally declining

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 2034

Notes:

1. The y-axis on this graph does not start at zero.
2. Generations are demographic cohorts grouped by years of birth and shared historical or cultural experiences. The span of a generation is approximate and can vary slightly depending on the source.

The following data identify specific cohorts by year, based on the standardised mean (average) ages of women giving birth. This is in relation to those born in 1979, which is the latest cohort to complete childbearing.

Figure 1 shows that women born in 1925 - who were part of the "Greatest Generation" and are considered to be the grandmothers of those born in 1979 - had an average completed family size of 2.12. Their "baby boomer" daughters, who were born in 1953, had a lower average completed family size of 2.05. The latest cohort considered to have completed their family are those born in 1979, towards the end of the "Generation X" era. Their average completed family size is 1.95, which is again lower than their grandmothers' and mothers'.

To maintain a population in the absence of migration, the "replacement rate" is considered to be 2.1. The grandmother's cohort was above the replacement rate, the mother's cohort was around the replacement rate, and the latest cohort is below replacement rate. This decreasing trend is projected to continue with the "Generation Z" daughters of the 1979 cohort who were born in 2008 and are projected to have an average of 1.48 children.

Baby girls born in 2026 - part of the "Beta Generation" - are projected to have a lower completed family size of 1.43.

Since records began, the peak completed family size was an average of 2.42 children for those women born in 1934 and 1935, part of the "Silent Generation". The lowest observed completed family size in the series was 1.89 for women of "Generation X" who were born in 1972 and 1973. Completed family size is projected to fall rapidly for women born in the later period of "Generation Y" and to continue to decline gradually for later generations.

Age at childbirth through the generations

Figure 2 shows the fertility trajectories for selected cohorts. While each cohort had a slightly lower completed family size than their mothers' cohort, the 1925 and 1953 cohorts followed very similar trajectories. The 1979 cohort had a lower average number of children throughout their late 20s and throughout their 30s than previous cohorts.

The projected trend for the daughters of the 1979 cohort, born in 2008, shows a much lower average number of children both throughout their childbearing years and on completion of their family. Girls born in 2026 are projected to have a similar, although slightly lower, average number of children throughout their childbearing years as those born in 2008.

Figure 2: Future generations are projected to have fewer births across their lifetime and have a lower completed family size than previous generations

Past and projected average number of children born, by mother’s age, for selected cohorts of women born between 1925 and 2026, England and Wales

Notes:

1. These data are presented in exact years. Figures should be interpreted as the average number of children a group of women have had up to a specific age. For example, figures for age 20 years represent cumulative fertility up to the day before their 20th birthday.

To look at how the age of childbirth has changed over time for different cohorts of women, we can look at the age by which there is an average of one child per woman. Women born in 1979 (the latest cohort to complete their family) had, on average, one child per woman by 31 years of age. This is higher than both their mothers' cohort (born in 1953), who reached this milestone by 27 years of age, and their grandmothers' cohort (born in 1925), by 28 years of age. The 2008-born daughters of the 1979 cohort are projected to have an average of one child per woman by 35 years of age. This reflects an increase in the age of childbearing for successive generations of women.

The proportion of women not having children has varied little across the cohorts. Of women born in 1979, 15.7% had no children; this is a slightly higher proportion than their mother's cohort (14.8%) but is lower than their grandmother's cohort (16.8%). There has, however, been a shift towards smaller families for the 1979 cohort, compared with their mother's. The proportion of women that have had one child increased from 12.4% (for women born in 1953) to 18.5% (for women born in 1979).

Male fertility

Male cohort fertility has been included in this release for the first time as official statistics in development. These statistics were not included previously because of differences in data collection at birth registration between men and women and in the time series of data available for men.

We have complete cohort data for men born between 1949 and 1959. There is incomplete digital data for cohorts born before 1949. A man's reproductive span is also less defined than a woman's. Within this release, we have considered a man's reproductive span to be between 15 and 65 years of age. Men born in 1959 would be 65 years of age in 2024 and considered to have completed their family. Data for men born from 1960 onwards are incomplete because the final reporting age will not yet have been reached.

For more information on the limitations of male cohort fertility data, see our Fertility for those born in different years, England and Wales quality and methods guide and our National Statistical blog on fertility figures.

Figure 3 compares the average number of children for men and women born in 1959 and 1979. The latest cohorts for which we have completed family size data is 1959 for men and 1979 for women. Achieved family size for men is lower than for women of the same age. This is because men tend to have children at older ages, compared with women. There was an average of one child per man by 33 years of age for men born in 1979, compared with 31 years of age for 1979-born women. This occurred by younger ages for men and women born in 1959 - by 31 years and 28 years of age, respectively.

Differences in achieved family size are particularly noticeable for those in their 20s and early 30s. While the gap does narrow for the 1959 cohort by the time women have completed their childbearing at 45 years of age, men do still have a lower average number of children at this point in their lives. The gap is wider for the 1979 cohorts at the same stage.

For the 1959 cohort of men, where we have complete family size data, the average number of children men have continues to increase slightly into their 50s and early 60s (reaching a completed family size of 2.00 children). This is slightly higher than the average number of children a woman born in 1959 had on completion of her family at 45 years of age (with an average of 1.98 children).

Differences in completed family size between men and women born in the same year may relate to several factors, including:

• the age difference between partners having children, and changes in this over time

• differences in the size of the resident population of men and women

It should also be noted that father's age has been imputed for sole birth registrations, which may also affect the comparability of the male and female data.

Figure 4: The age at which both men and women are having children has increased over time

Age-specific fertility rates for men and women, born in selected years, England and Wales

Notes:

1. These data are presented in completed years. Figures should be interpreted as the number of live births per 1,000 women or per 1,000 men at their age at their last birthday. For example, rates for those aged 40 years will include births up to the day before their 41st birthday.  
2. Age-specific fertility rates for male cohorts are shown up to age 55, however, they are published for higher ages. For men born in 1979, they are shown up to the age achieved in 2024.

Figure 4 shows that men tend to have children at older ages compared with women born in the same year. The difference is consistent across the four cohorts, with the most common age for having children generally being two to three years older for men than for women. The age at which both men and women have children has increased over time.

For each cohort shown, age-specific fertility rates are higher for women than men at younger ages. For the 1949 cohort, the age at which male rates surpassed those of women born in the same year was at 28 years of age. For the 1959 cohort, this was at 29 years of age. For the 1969 cohort, this rose to 31 years of age and for the 1979 cohort this was at 33 years of age. This higher rate of live births per 1,000 men, compared with women born in the same year, continues throughout their 30s and 40s, with steadily declining rates for men into their 50s.

Births

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

Cohort

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

Completed family size

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

For this bulletin, we look at women between 15 and 45 years of age and men between 15 and 65 years of age. This is because the number of women/men who have children before 15 years of age and after 45/65 years of age are small, and do not affect the overall patterns. Births to younger women/men are included at 15 years of age. 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.

Our final "completed family size" rates for the 1979 cohort include births to mothers aged 45 years in 2024. It also includes births in 2024 to mothers aged 46 years and over for women who were born in earlier years. 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. The same applies to men for the 1959 cohort, which will include children to fathers aged 65 years in 2024 and also those aged 66 years and over born in earlier years.

Completed age

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

Exact age

The ages of women or men are generally presented in this bulletin as exact years. Therefore, figures should be interpreted as the average number of children a woman or man has had up to that birthday. Cumulative fertility through a woman's/man's lifetime up to the exact age of 40 years includes any live-born children they have had up to the day before their 40th birthday.

Standardised mean age

The standardised mean (average) age is a measure that removes 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 or male population, by single year of age of mother or father. 

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

We provide information on strengths, limitations, appropriate uses, and how the data were created in our Fertility for those born in different years, England and Wales, quality and methods guide.

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. Stillbirths, adopted or fostered children, and stepchildren are excluded.

For this bulletin, we look at women between the ages of 15 and 45 years and men between the ages of 15 and 65 years. A small number of women and men complete their childbearing after this, but these do not affect the overall patterns. Births to women aged 46 years and over and to men aged 66 and over are included by using a proxy. This is based on the number of births to woman aged 46 years and over and for men aged 66 and over, in previous cohorts. 

Population estimates for mid-2022 and mid-2023 were revised in summer 2025. These revisions have been fed through to this publication. Changes to the mid-year estimates, which are used to calculate fertility rates, may have resulted in small differences to previously published data. 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 2024-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 fertility among women and men in England and Wales by the year of birth of the mother/father. The year is approximate, and is based on calendar year of occurrence and the age of mother or father at childbirth. For example, a woman aged 32 years giving birth in 2012 could have been born in 1979 or 1980; they are counted in the 1980 cohort. 

Male cohort family size distributions and some cumulative fertility data are not available because the same data are not collected for men 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. Information on male completed family size is now available. A man's reproductive span is not as well defined as a woman's, so a longer time series is needed to calculate cohort measures. As we now have a long enough time series, we have included that data where possible. More information about male period fertility rates is available in our Birth characteristics in England and Wales bulletins. 

We provide further information on data quality, legislation, and conceptual procedures in our User guide to birth statistics.

Statistical designation

Accredited official statistics

The Office for Statistics Regulation independently reviewed our fertility for women born in different years statistics 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".

Official statistics in development

The cohort fertility statistics for men are new for this publication and are labelled as "official statistics in development". We are developing how we produce the statistics to improve their quality.

Once we have completed the developments, we will review the statistics with the Statistics Head of Profession. 

If the statistics meet trustworthiness, quality and value standards based on user feedback, we will remove the "official statistics in development" label to publish under the "official statistics" label. 

If they do not meet trustworthiness, quality and value standards, we will further develop them and might stop producing them.

We will inform users of the outcome of our, and any OSR, review and any changes.