Current trends and issues in British fertility analysis

Jessica ChamberlainFertility Analysis Unit, Office for National Statistics

Thanks to Steve Smallwood, John Jeffs and Baljit Gill

Overview

1) Current trends in fertility• Background• Analysis of increases - Age

- Geography

- Registration type

- Country of birth

- Parity

2) Current issues in fertility • Fertility and migration

• Subnational fertility

Trends in the TFR

Total fertility rate, England and Wales 1938-2004

0

0.5

1

1.5

2

2.5

3

3.5

1938 1943 1948 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003

Children per woman

Post World War Two baby boom

1960s baby boom

Late 1970s low fertility

1930s low fertility

Recent rise in fertility

Trends in childbearing behaviour

• Decline in completed family size. Decrease from 2.46 children for 1934 cohort to 1.99 for most recent cohort to complete childbearing.

• Increase in proportion of women remaining childless. Increase from 9 per cent of women born in 1945 to around 20 per cent for women soon to complete childbearing.

• Increased mean age at first birth • Childbearing to women in their 20s has decreased

and increased to women in their 30s.

Recent increase in fertility

• Record low TFR of 1.63 in 2001.• Increase every year since then.• The rise from 2002 to 2003 was the largest absolute and

proportional change in TFR since 1979.

Year TFR Absolute change

Percentage change

2001 1.632002 1.65 0.02 1.12003 1.73 0.08 4.62004 1.78 0.06 3.2

Has this increase occurred all over the UK?

ScotlandYear TFR Absolute Percentage

change change2001 1.492002 1.48 -0.01 -0.42003 1.54 0.06 3.62004 1.60 0.06 3.9

Northern IrelandYear TFR Absolute Percentage

change change2001 1.802002 1.77 -0.03 -1.62003 1.81 0.04 2.32004 1.88 0.07 3.5

Has this increase occurred all over England and Wales?

• This rise has occurred all over England and Wales to varying degrees.

• In 2003 all GORs except the North East saw rises of 4.3 to 4.8 per cent in their TFR from 2002. In 2004 the TFR increased by 3 or more per cent everywhere except the South East.

2001 2002 2003 2004NORTH EAST 1.56 1.60 1.66 1.71NORTH WEST 1.66 1.66 1.73 1.81YORKSHIRE AND THE HUMBER 1.66 1.67 1.76 1.82EAST MIDLANDS 1.61 1.63 1.70 1.76WEST MIDLANDS 1.74 1.75 1.84 1.91EAST OF ENGLAND 1.67 1.69 1.77 1.83LONDON 1.61 1.63 1.71 1.76SOUTH EAST 1.62 1.63 1.71 1.77SOUTH WEST 1.58 1.62 1.70 1.74WALES 1.66 1.63 1.71 1.77

TFR

Does the increase apply across women of all ages?

Age-specific fertility rates, England and Wales, 1980-2004

0

20

40

60

80

100

120

140

1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004

Year

Births per 1,000 women

25-29

30-34

20-24

35-39

15-19

40-44

Registration type

• Percentage increase in births jointly registered both at same address and at different addresses was greater than the overall percentage increase in births.

• Percentage increase in births registered by the mother alone was below the overall percentage increase in the number of births.

Percentage change in number of births from previous year, by registration type

All births Married Unmarried SoleSame address

Different address

registration

2002 0.2 -0.7 1.6 2.4 2.0 -1.42003 4.1 2.8 5.9 5.7 8.5 3.92004 2.9 1.6 4.6 4.7 7.3 1.1

Jointly registered

Country of birth of parents

• Since 1995 the proportion of births occurring to mother’s born outside the UK has been rising.

• This rise became steeper between 1999 to 2004. • In 2004 19.5 per cent of all births were to women

born outside of the UK.

Percentage change in number of births on previous year

Country of birth of mother 2002 2003 2004

Total 0.2 4.1 2.9United Kingdom -1.2 3.0 1.8Total outside UK 7.1 8.7 7.4

Parity

• Increases in probability of progression to first birth, particularly for older women in last two years.

• So the number of women who would remain childless has decreased from one in four women to one in five.

• Probability of having a second birth has not increased back to previous levels, but the number of women exposed to having a second birth has increased.

• Some of low fertility from 1995 onwards appears to be associated with a decline in women in their 30s progressing to have a second birth.

Period Parity Progression ratiosYear 0-1 1-2 2-3 3-4 4-5+1980 0.835 0.795 0.399 0.342 0.3621990 0.795 0.810 0.422 0.357 0.4292000 0.762 0.764 0.380 0.335 0.4042001 0.757 0.757 0.375 0.332 0.4072002 0.762 0.755 0.376 0.338 0.4132003 0.780 0.764 0.394 0.352 0.4262004 0.792 0.769 0.407 0.367 0.435

Percentage changes on previous year's PPPRYear 0-1 1-2 2-3 3-4 4-5+2000 -1.3% -1.7% -2.9% 0.8% 3.5%2001 -0.6% -0.9% -1.2% -0.8% 0.6%2002 0.6% -0.3% 0.3% 1.9% 1.4%2003 2.4% 1.2% 4.8% 4.0% 3.2%2004 1.6% 0.7% 3.3% 4.3% 2.3%

Occurrence-exposure rates- 1st births

0

20

40

60

80

100

120

140

14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

Age

Fir

st

bir

ths

pe

r 1

,00

0 c

hild

les

s w

om

en

1980199020002004

Occurrence-exposure rates - 2nd births

0

50

100

150

200

250

300

14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

Age

Se

co

nd

bir

ths

pe

r 1

,00

0 w

om

en

wit

h o

ne

ch

ild

1980199020002004

Occurrence-exposure rates - 2nd births

-

50

100

150

200

250

1965 1970 1975 1980 1985 1990 1995 2000

Se

co

nd

bir

ths

, pe

r 1

,00

0 w

om

en

wit

h o

ne

ch

ild

Age 30

Age 35

Is this rise the start of a new trend?

• Fertility can vary year to year due in part to change in timing of births.

• There were substantial rises in fertility in 1978 and 1979 after a period of record low fertility had occurred, however fertility fell again in the early 1980s.

• 2000 to 2002 were years of particularly low fertility, so may be some short term catching up of births.

• The rise in births to women in their 30s may indicate the continued long term trend of postponement of births to older ages.

• May, in part, be an effect of the timing of births of migrants.

Future Projects

• Two future projects that the Fertility Analysis Unit at ONS are undertaking to further understanding of fertility within England and Wales:

1) Relationship between migration and fertility

2) Calculating and analysing subnational fertility

Births to non-UK born mothers

Percentage of births to mothers born outside the United Kingdom, England and Wales 1969 - 2004

0

5

10

15

20

1969 1974 1979 1984 1989 1994 1999 2004

Percentage

Gross female international migration

Gross inflow of female international migrants by age, England and Wales 1993-2003

0

50

100

150

200

250

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Thousands

Under 15 15-44 45-64 65 and over

Source: MN, Table 2.9

1) Fertility and migration

• Disruption hypothesis• When standardised for age women have lower

fertility before migration than women in the destination country.

• Then migrants show a rise and peak in fertility after migration.

• After period of time fertility of immigrants declines and may become similar to the fertility of native born women.

• Migration and family building in many cases are interrelated processes.

Fertility of immigrant women by age at entry into France, 1991-1998

Source: Toulemon (2004)

Literature

• This relationship has been shown in studies in America, Canada, France, Sweden and Norway.

• Age at entry and country of origin affect fertility pattern before and after migration

• Different types of migration to consider: economic migration and migration to join family. Also refugees and asylum seekers likely to have a different pattern.

• Toulemon (France) - Need to calculate the TFR for overseas born women taking into account age at entry and duration of stay so as not to overestimate fertility.

Using the General Household Survey (GHS) for England and Wales

• GHS contains: age, country of birth, year of entry to UK and fertility history for 1971-1996, 1998 and 2000-2004 surveys.

• Numbers available in GHS large enough - 615 women born outside of the UK in 2002 GHS.

• May need to combine several year’s of GHS data.• Also have fertility intentions data.• Other possible data sources? BHPS?

2) Subnational fertility - Issues

• Method of standardisation• Confidence intervals on fertility rates• Confidence intervals on population, from census• Other geographies, e.g. rural/urban, primary care

organisations• Time trends and changing boundaries• Correlations with other factors e.g. level of

deprivation, employment of women

Highest and lowest LA Total Fertility Rates, England and Wales 2003

Source: http://www.nchod.nhs.uk - TFRs with confidence intervals for 2003 for LAs, PCOs and other geographies.

Local Authority TFRLower limit Upper limit

Lowest 10 TFRs City of London LB 0.82 0.61 1.03Cambridge CD 1.12 1.05 1.19Westminster, City of LB 1.22 1.18 1.27Exeter CD 1.27 1.2 1.35Kensington and Chelsea LB 1.29 1.24 1.35Durham CD 1.29 1.19 1.38Oxford CD 1.34 1.27 1.40Norwich CD 1.35 1.28 1.42York UA 1.37 1.31 1.43Camden LB 1.38 1.33 1.43

Highest 10 TFRs Newham LB 2.34 2.27 2.40Blackburn with Darwen UA 2.27 2.17 2.36Bradford MCD 2.23 2.17 2.28Luton UA 2.23 2.16 2.31Hackney LB 2.19 2.12 2.25Oldham MCD 2.19 2.11 2.27Hyndburn CD 2.19 2.06 2.31Walsall MCD 2.11 2.04 2.19Mid Devon CD 2.11 1.96 2.26Slough UA 2.05 1.95 2.14

95% Confidence Interval

Any questions or suggestions?