Childbearing for women born in different years, England and Wales: 2019

The changing composition of families over time, comparing the fertility of women of the same age and the number of children they have had.

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Cyswllt:
Email Amanda Sharfman

Dyddiad y datganiad:
4 December 2020

Cyhoeddiad nesaf:
To be announced

1. Main points

  • Women in England and Wales born in 1974 who completed their childbearing in 2019, had on average 1.92 children, a slight increase on women born in 1973 (1.89 children).

  • Nearly half (49%) of women born in 1989 (the most recent cohort to reach age 30 years) remained childless by their 30th birthday, compared with 38% for their mothers’ generation and just over one-fifth for their grandmothers’ generation (1961 and 1934 cohorts respectively).

  • The most common age at childbirth for women born in 1974 was 31 years, an increase compared with 23 years for their mothers’ generation born in 1948.

  • Two-children families remain the most common family size (37%) but a similar proportion of women born in 1974 had either no children or just one child (36% combined).

Statistician’s comment

“Average completed family size has been falling since the cohort of women born in 1935 and has been below two children since the late 1950s cohorts. Following a low of 1.89 children for women born in the previous two years’ cohorts, we see a slight rise to 1.92 for women born in 1974.

We continue to see a delay in childbearing, with nearly half of women born in 1989 remaining childless by their 30th birthday compared to 1 in 5 in their grandmother’s generation. The fertility patterns of women born more recently indicate this trend is likely to continue, with women born in 1995 showing lower levels of fertility in their 20s compared with previous cohorts.”

Amanda Sharfman, Centre for Ageing and Demography, Office for National Statistics

Follow Centre for Ageing and Demography on Twitter @RichPereira_ONS

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2. Average completed family size

Women born in 1974, who are assumed to have completed their childbearing in 2019, had on average 1.92 children (Figure 1), a slight increase on women born in 1973 (1.89 children). In comparison, women born in 1948, who are assumed to be the generation of mothers of the women born in 1974, had a larger average completed family size of 2.11 children per woman.

Average completed family size has been falling since 1935 and has been below two children since the cohort of women born in 1958. However, the 1974 cohort shows a small uptick in average completed family size. In the short term, the average number of children is likely to remain at or above 1.92 based on current levels of cumulative fertility for subsequent cohorts (women born in the mid-to-late 1970s).

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 completed family size.

The average number of children women have by age 30 years has been steadily falling from a peak of 1.89 children per woman in 1941. Women born in 1974 had on average just one child per woman (1.00) by age 30 years, compared with 1.62 children per woman for women born in 1948 (their mothers' generation).

Despite women born in 1973 and 1974 both having on average just one child per woman (1.00) by age 30 years, by the end of childbearing those born in 1974 had a higher average completed family size (1.92 children per woman) than the 1973 cohort (1.89 children per woman). This is because women born in 1974 had more births on average in their 30s and 40s than those born in 1973.

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3. Childlessness

Just as the average number of children women have by age 30 years has fallen, the proportion of women who reached their 30th birthday without having a child has changed substantially over time (Figure 2). Nearly half (49%) of women born in 1989 (the most recent cohort to reach age 30 years) remained childless by their 30th birthday, compared with 38% for their mothers’ generation (1961 cohort) and 21% for their grandmothers’ generation (1934 cohort).

Figure 2 also shows that despite an increasing trend in childlessness by age 30 in recent years, the percentage of women who are childless by the end of their childbearing years has remained fairly consistent for women born since the late 1950s. This suggests that women are delaying childbearing rather than not having children.

Of women born in 1974 who completed their childbearing in 2019, 18% remained childless, compared with 19% for women born in 1973.

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 equivalent estimates of the proportion of men who have not fathered a child.

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4. Most common age at childbirth

The standardised mean age of mother has been increasing since the mid-1970s and reached a record high at 30.7 years in 2019.

The most common age at childbirth for women born in 1974 who reached age 45 years in 2019 was 31 years, an increase compared with 23 years for their mothers’ generation born in 1948. Figure 3 shows the ages of women giving birth for each of the selected cohorts.

For the 1965 and earlier cohorts, the highest number of births per 1000 women occurred for women between the ages of 23 and 26 years. The highest number of live births per 1,000 women occurred at the age of 31 years in the 1974 and 1985 cohort (who have yet to complete their childbearing years). This is evidence that women are tending to delay their childbearing. The most recent cohorts visible on the chart (women born in 1995 and 2000) are so far displaying a "flatter" trend, showing the recent decrease in births to teenage mothers and so far, the 1995 cohort is showing noticeably lower fertility in their 20s than the 1985 cohort.

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

Some of the reasons for women delaying childbearing may include:

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5. Completed family size

The average completed family size for women born in 1974 (1.92 children per woman) is smaller than their mothers’ generation born in 1948 (2.11 children per woman), but two-children families remain the most common family size (Figure 4).

A lower percentage of women born in 1974 had two or more children than women born in 1948, whereas a higher proportion had just one child or remained childless by the end of their childbearing years.

Women born in 1974 are as likely to have either no children or just one child (36%), as they are to have a two-child family (37%).

Figure 5 shows changes in family size over time between the 1920 and 1974 cohorts. Two-children families continue to be the most common family size, including for women born in both 1974 and 1948 (also shown in Figure 4). 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 1974 cohorts.

The proportion of large family sizes (those including four or more children) among women born in 1974 (11%) is the same as for their mothers’ generation. Large family sizes peaked among women born in the early-to-mid 1930s before falling post-war. This reduction, along with the increase in the proportion of childless women, can be clearly noted when looking at Figure 5 for the post-war generations.

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6. Childbearing for women born in different years data

Childbearing for women born in different years, England and Wales: 2019
Dataset | Released 4 December 2020
Annual analysis of fertility by cohort for women in England and Wales.

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7. Glossary

Cohort

A group of women with the same year of birth.

Completed family size

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

Childlessness

The proportion of women who had not had a live birth by a specific age. No distinction is made between voluntary and involuntary childlessness (that is, no distinction is made between childless and childfree women).

Exact age

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.

Standardised mean age

The standardised mean (average) age (for example, at birth or marriage) is a measure that eliminates the impact of any changes in the distribution of the population by age and therefore enables trends over time to be analysed. Standardised means are calculated using rates per 1,000 female population by single year of age of mother.

Further definitions are available in the glossary of terms in our User guide to birth statistics.

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8. Measuring the data

Birth statistics represent births that occur and are then registered in England and Wales. Figures are derived from information recorded when live births and stillbirths are registered as part of civil registration, a legal requirement; these data represent the most complete data source available.

In England and Wales, the registration of births is a service carried out by the Local Registration Service in partnership with the General Register Office (GRO).

Further linkage of the birth registration to the NHS birth notification is conducted within the Office for National Statistics (ONS) to obtain the age of the mother where this was missing on the birth registration.

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.

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.

A woman’s childbearing is assumed to start at age 15 years and end at age 45 years (the day before her 46th birthday). While some women complete their childbearing after aged 45 years (and this number has been increasing), the numbers involved do not affect the overall patterns with fewer than four in every thousand live births being to women aged 45 years or older. Births to women aged 45 years and older are included in the supporting dataset.

The estimates have been updated with 2019 births, which means that completed family size for women born in 1974 (women reaching age 45 years in 2019) is presented for the first time. Women born in 1989, who reached age 30 years in 2019, are also used as a comparison group, as age 30 years may be considered the mid-point of a woman’s childbearing years.

Women born in 1948 are assumed to be the generation of mothers of the women born in 1974 based on the average age of mothers at childbirth in 1974 being 26 years.

Women born in 1934 are assumed to be the generation of grandmothers and those born in 1961 the generation of mothers of the women born in 1989 (the most recent cohort to reach age 30 years). This is based on the average age of mothers at childbirth being 28 years in 1989 and 27 years in 1961.

Coronavirus and birth statistics

The data in this publication are not affected by the coronavirus (COVID-19) pandemic as they relate to births for the year ending 31 December 2019. In normal circumstances, births should be registered within 42 days and our annual data extract only includes births registered before 25 February. For more information, please see our User guide to birth statistics.

Because of the coronavirus pandemic and the announcement of lockdown measures, birth registration services in England and Wales were temporarily suspended in March 2020. Since June 2020, birth registrations have restarted where it is safe to do so. In line with the Office for National Statistics' (ONS') response on the production of statistics during the pandemic, we are monitoring the implications of any delays in 2020 births registrations and exploring the possibility of using alternative data sources to estimate 2020 births data in a more timely manner.

Quality

More quality and methodology information on strengths, limitations, appropriate uses, and how the data were created is available in the Births Quality and Methodology Information (QMI) report.

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9. Strengths and limitations

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

This release presents statistics on childbearing among women in England and Wales by the year of birth of the mother. The year of birth of the mother is by necessity approximate because, prior to 1963, data are available only by calendar year of occurrence and age of mother at childbirth. For instance, women aged 32 years giving birth to children in 2012 could have been born in either 1979 or 1980; for convenience however, such women are regarded as belonging to the 1980 cohort.

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.

National Statistics status for Births in England and Wales

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

Date of most recent full assessment: September 2011.

Most recent compliance check that confirms National Statistics status: September 2011.

The improvements we have made since the last review include:

  • revisions to the way statistics are produced are explained in the User guide, detailing the year the change took place and reason why

  • in cases where corrections were implemented, they were accompanied by explanations of the change and the reasons why

  • where applicable, we added background information into our User guide and QMI to inform the user of the differences in methods between the UK countries and the reasons underlying these differences

  • following a consultation on proposed changes to statistics, we made changes in 2018 to the way that birth statistics are published; five explorable datasets are now released in July alongside the first release of annual births data, which means more detailed birth data (including small area geographies) are now available in a timelier manner

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.

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Manylion cyswllt ar gyfer y Bwletin ystadegol

Amanda Sharfman
pop.info@ons.gov.uk
Ffôn: +44 (0)1329 444661