Childbearing for women born in different years, England and Wales: 2021 and 2022

• Women in England and Wales who were born in 1977 have an average completed family size of 1.94 children (before the age of 46 years); this is the highest average since those born in 1962, but a lower average compared with 2.07 children for their mothers' generation (assumed to be those born in 1950). 

• Of women born in 1977, 16% had not had a child before the age of 46 years; this is lower than the levels seen for those born in the 1960s, although still higher than their mother’s generation (14%).  

• Two-child families remain the most common family size (38%), however this is a decrease in the proportion of those having two children, when compared with their mothers' generation (44%). 

• Women are having children later compared with previous generations; the most common age for women born in 1977 to give birth was 31 years, compared with approximately 10 years younger for their mother's generation. 

• Of those women born in 1993, 44% have had one or more children before 30 years of age; this compares with 58% of their mother's generation (born in 1965) and 81% of their grandmother's generation (assumed to be those born in 1938).

Family size 

The completed family size for women born in 1977 was, on average, 1.94 children. 

Immediately before this, there was an all-time low recorded of 1.89 children for women born in 1972 and 1973. There has been a slight increase in the average completed family size year on year for four consecutive years. The current average of 1.94 was last seen 15 years ago, for women born in 1962. 

In comparison, women born in 1950 had a larger average completed family size of 2.07 children. These women are assumed to be the generation of mothers of the women born in 1977 (based on the standardised mean age of a mother in 1977 being 26.6).

The average number of live-born children that a woman has had before she is aged 30 years gives an indication of trends in fertility for cohorts of women born more recently. However, this is becoming less indicative of trends in completed family size, as women increasingly have children when they are aged 30 years or over. 

Mothers born between 1940 and 1941 had the highest average number of children before they were aged 30 years, at 1.89 (Figure 1). From 1941, there was a steady decline to 0.98 to those mothers born in 1978, shortly followed by an increase for mothers born between 1979 and 1987. Since 1988, there has again been a continuing pattern of decline. The latest cohort of women to reach 30 years of age has had the lowest average number of children, at 0.8 children per woman.

The average family size has been decreasing since mothers born in the mid-1930s. However, two-children families have remained the most common family size across both generations, with 38% of those born in 1977 and 44% of those born in 1950, having had two children.

Most common age at childbirth 

For women born in 1977, the most common age to give birth was 31 years. This has remained the most common age to give birth for the last six cohorts. This is an increase in the most common age of childbirth when compared with women born in 1950, who were most likely to give birth in their early twenties. These women were assumed to be their mother's generation based on the standardised mean age of a mother born in 1977.

Trends in fertility rates have changed over time. There has been a shift in the most common age of childbirth, with earlier cohorts having children largely in their twenties, while those born from the early 1970s onwards are having children largely in their thirties.

The latest cohort shown in Figure 3, (women born in 2000) is so far displaying a "flatter" trend, having noticeably lower fertility in their early twenties than previous cohorts of women. The impact this may have on the average completed family size in the future is not yet known. 

For more information from the Centre for Ageing and Demography you can follow @RichPereira_ONS on Twitter.

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 as 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 analysis, we look at women between the ages of 15 and 45 years. This is because while some women do have children before the age of 15 years and after the age of 45 years, the numbers 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 1977 cohort include births to mothers aged 45 years and under in 2022. It also includes births 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 1977 cohort. Births to mothers aged 46 years and over remain a small proportion of total births. These final rates are used throughout this bulletin, when referring to the completed family size of the latest cohort. 

Completed age

The ages of women are presented in Figure 3 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 impact 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.

Quality 

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

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

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 analysis, 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. 

Population estimates are used to calculate fertility rates. Our 2012 to 2021 population estimates have been updated to reflect Census 2021 results. Therefore, our 2012 to 2020 childbearing data have been updated. The 2021 and 2022 childbearing data have been published for the first time, alongside this updated data. 

Coronavirus and birth statistics

In March 2020, birth registrations in England and Wales were temporarily suspended, and restarted in June 2020, because of the coronavirus (COVID-19) pandemic. Normally, births are registered within 42 days, but this was only true of 58% of births in 2020. A later than usual cut-off point was used (August 2021) and any late registrations after this date are included in the 2021 births data, as is normal practice. For more information, see our User guide to birth statistics and Births in England and Wales explained: 2020 article.

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 is 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; but are counted in the 1980 cohort. 

Male cohort fertility rates cannot be calculated, 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, preventing 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.

National Statistics status for Births in England and Wales

Our statistics have National Statistics status. This means our statistics meet the highest standard of trustworthiness, quality and public value, and it is our responsibility to maintain compliance with these standards. 

Our most recent UK Statistics Authority full assessment was published in September 2011. Several improvements have been made since this review. 

• We have explained revisions to the way statistics are produced in our User guide to birth statistics. 

• With any corrections made, we have explained the change and why it has been made. 

• Background information has been added to our User guide to birth statistics and our Births QMI about the differences between UK countries' methods. 

• Changes were made in 2018 to the way birth statistics are published. 

In 2012, changes were made to the Population (Statistics) Act 1938; information on the number of previous children and whether a woman was previously married is now collected from all mothers. In 2016, the registration system was updated to allow the collection of these data.