Infant Mortality Analysis Update (2) 2011Gestation

BirthweightAge of Mother

EthnicityCause of death

Jonnie Dance – Senior Public Health Analyst Teresa Keegan - Public Health Information Analyst Including analysis conducted by:Helen Brown – Head of Intelligence Public HealthSimon Chappell – Public Health Trainee Analyst

Glossary

• Gestation length of pregnancy• Parity number of births to one woman• Pre-term birth birth prior to 37 full weeks

gestation• Low Birth Weight birthweight of infant < 2.5kg• Very Low Birth Weight birthweight <1.5Kg• Deprivation quintile Post-coded localities ranked

according to the Index of Multiple Deprivation and divided into five levels across Bradford

Glossary cont…• Infant mortality Death of a live born infant

prior to one year of age.• Infant mortality rate number of infant deaths

(IMR) per 1,000 live births• Neo-natal mortality death of live born infant prior to

28 days of age• Post-neonatal mortality Death of an infant between

28 days to one year of age• Stillbirth infant that dies prior to birth

and after 24 weeks gestation• Still birth rate Number of stillbirths per 1000

stillbirths and live births

Gestation – key points• There has been relatively little change in the proportion of

premature births over the last 15 years - between 7-9%.• There is a deprivation gradient with more premature births

in the most deprived areas.• There has been a slight increase, since 2003, in infant

mortality rates amongst full term births.• There has been a steady increase in stillbirth rates amongst

full term births since 1996.

Proportion of all births by gestation category, Bradford and E&W

• Little overall change in proportion for each category of low gestation although a decrease in the proportion of 31-36 week babies in recent years

0%

1%

2%

3%

4%

5%

6%

7%

8%

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

% o

f to

tal b

irth

s

Bradford <24

Bradford 24-30

Bradford 31-36

Eng&Wales <24

Eng&Wales 24-30

Eng&Wales 31-36

Premature birth rate by deprivation quintile over time (5-year rolling)

• Deprivation gradient seen for premature births• Relatively little change seen between the most and least deprived

0

1

2

3

4

5

6

7

8

9

10

1996-2000 1997-2001 1998-2002 1999-2003 2000-2004 2001-2005 2002-2006 2003-2007 2004-2008 2005-2009

Prem

atur

e Bi

rth R

ate

per 1

00 B

irths

Most deprived

2nd most deprived

3rd most deprived

2nd least deprived

Least deprived

0

1

2

3

4

5

6

1996-2000

1997-2001

1998-2002

1999-2003

2000-2004

2001-2005

2002-2006

2003-2007

2004-2008

2005-2009

1996-2000

1997-2001

1998-2002

1999-2003

2000-2004

2001-2005

2002-2006

2003-2007

2004-2008

2005-2009

Premature Full term

Mort

alit

y r

ate

per

1000 b

irth

s

Neonatal

Postneonatal

Infant

Still birth

Mortality rates for premature and full term births

• Infant mortality rates have risen in full term births since 2003.• Still birth rates have steadily risen across the whole time period, with

the 2005-09 rate being significantly higher than the 1998-02 rate

Gestation – key points• There has been relatively little change in the proportion of

premature births over the last 15 years - between 7-9%.• There is a deprivation gradient with more premature births

in the most deprived areas.• There has been a slight increase, since 2003, in infant

mortality rates amongst full term births.• There has been a steady increase in stillbirth rates amongst

full term births since 1996.

Birthweight (BW) – Key points• There is a clear deprivation gradient seen for low and

very low BW babies.• Mortality is much higher for low BW babies (approx 10x

higher than those weighing > 2500g) and much higher for very low BW (approx 10x higher than low BW)

• Infant mortality rates have changed little over the last 15 years for ‘normal’ BW babies but have decreased for Low BW and very low BW babies.

• Still birth rates have increased across all birth weights but most for ‘normal’ BW babies.

0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

12.0%

1996-1998

1997-1999

1998-2000

1999-2001

2000-2002

2001-2003

2002-2004

2003-2005

2004-2006

2005-2007

2006-2008

2007-2009

% o

f tot

al b

irths

1. Mostdeprived

2

3

4

5. leastdeprived

Proportion of low birthweight births by deprivation quintile (3-year rolling)

• Clear deprivation gradient with a higher proportion of low weight births (1500-2500g) in the more deprived areas.

• Excludes v low birthweight – similar but less vivid picture

Distribution of birthweight for each deprivation quintile, 2000-2009

• Gradient seen with lower BW babies for the most deprived areas

0%

1%

2%

3%

4%

5%

6%

7%

8%

<1000 1000-1499 1500-1999 2000-2499

Birthweight /g

Per

cent

age

Birt

hs in

eac

h de

priv

atio

n qu

intil

e

1. Most deprived

2

3

4

5. Least deprived

Mortality Rates for different birthweight babies, Bradford and E&W, 2000-2009

• There is a large difference in mortality rates between normal, low and very low BW (approximately a factor of 10 difference between each category).

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280

Neonatal

Postneonatal

Infant

Still birth

Neonatal

Postneonatal

Infant

Still birth

Neonatal

Postneonatal

Infant

Still birth

No

rmal B

WLow

BW

Ve

ry low

BW

Mortality rate per 1000 births

Bradford rate'

Eng&Wales rate'

Mortality rates for >2500g BW babies

• Overall mortality for >2500g babies has not statistically significantly changed since 1996 – 2000.

• Still birth rates have increased consistently, but this is not statistically significant

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

1996-2000

1997-2001

1998-2002

1999-2003

2000-2004

2001-2005

2002-2006

2003-2007

2004-2008

2005-2009

Mort

alit

y r

ate

per

1000 b

irth

s

Neonatal

Postneonatal

Infant

Still birth

Birthweight (BW) – Key points• There is a clear deprivation gradient seen for low and

very low BW babies.• Mortality is much higher for low BW babies (approx 10x

higher than those weighing > 2500g) and much higher for very low BW (approx 10x higher than low BW)

• Infant mortality rates have changed little over the last 15 years for ‘normal’ BW babies but have decreased for Low BW and very low BW babies.

• Still birth rates have increased across all birth weights but most consistently for babies with a BW >2500g.

• Stillbirths – rising in full-term, > 2500g babies

Age of mother – key points• Bradford Infant Mortality rates are higher across all age

bands than E&W rates.• IM rates in children born to younger mothers and older

mothers is falling – but not so in the 25-34 band which appears to be most adrift from national levels.

0

1

2

3

4

5

<20 20-24 25-29 30-34 35-39 40+ <20 20-24 25-29 30-34 35-39 40+ <20 20-24 25-29 30-34 35-39 40+ <20 20-24 25-29 30-34 35-39 40+

Neonatal Postneonatal Infant Still birth

Rate

ratio

Ratio of Bradford to England Mortality rates by age of mother, 2000-2009

• Biggest differences in rates compared to Eng&Wales are seen for mothers aged 25-34

• Even though rates higher for 40+ it is the women aged 20-39 that have significantly higher than expected still births in Bradford compared to E&W

0

1

2

3

<20 20-24

25-29

30-34

35-39

40+ <20 20-24

25-29

30-34

35-39

40+ <20 20-24

25-29

30-34

35-39

40+ <20 20-24

25-29

30-34

35-39

40+

Neonatal Postneonatal Infant Still birth

Rate

ratio

Ratio of Bradford Mortality rates by age of mother, 2003-2009 (compared to 1996-2002)

• Across most age bands mortality rates have decreased (although not sig.). Mothers aged 30-34 however have seen an increase in infant mortality and still birth rates.

• Age of Mothers 40+ have seen the biggest decrease in mortality, and this is significant for still births.

Infant mortality rate by age of mother

• Rates higher than England and Wales across all mother ages, and highest for mothers under 20 years.

• Large fluctuation for 40+ mothers due to small numbers

0

2

4

6

8

10

12

14

16

18

20

1996-2000

1997-2001

1998-2002

1999-2003

2000-2004

2001-2005

2002-2006

2003-2007

2004-2008

2005-2009

1996-2000

1997-2001

1998-2002

1999-2003

2000-2004

2001-2005

2002-2006

2003-2007

2004-2008

2005-2009

Bradford Eng&Wales

Rat

e pe

r 10

00 b

irths

<20

20-24

25-29

30-34

35-39

40+

Age of mother – key points• Bradford Infant Mortality rates are higher across all age

bands than E&W rates.• IM rates in children born to younger mothers and older

mothers is falling – but not so in the 25-34 band which appears to be most adrift from national levels.

Ethnicity – key points

• Two biggest groups are White and Pakistani

• Infant Mortality rates higher in Pakistani and ‘Other’ populations.

• ‘Other’ ethnicities are:African Any other Asian backgroundAny other Black background Any other Ethnic GroupAny other Mixed background BangladeshiCaribbean ChineseIndian Other Asian BackgroundOther Black background Other Ethnic groupOther Mixed background White and AsianWhite and Black African White and Black Caribbean(Office for National Statistics Classification)

Infant mortality by Ethnic group, 2000-2009 (Eng&Wales 2005)

• Infant mortality rates are significantly higher for the White population in Bradford than in the White population of E&W.

• The rate for the Pakistani population is also higher than nationally although not statistically significant.

0

2

4

6

8

10

12

14

16

White Pakistani 1stgen

Pakistani 2ndgen

Pakistani total Other+ Total

Rate

per

1000 liv

e b

irth

s

Bradford

Eng&Wales

Neonatal and Post neonatal mortality rates by Ethnic group, 2000-2009 (Eng&Wales 2005)

• Although a higher proportion of deaths are neonatal (60%), Post neonatal mortality rates for all ethnic groups are more markedly higher than nationally.

0

1

2

3

4

5

6

7

White Pakistani 1stgen

Pakistani 2ndgen

Pakistani total Other+ Total

Rate

per

100

0 liv

e bi

rths

Bradford

Eng&Wales

0

1

2

3

4

5

6

7

8

9

10

White Pakistani 1stgen

Pakistani 2ndgen

Pakistani total Other+ Total

Rat

e pe

r 100

0 liv

e bi

rths

Bradford

Eng&Wales

Neonatal Post neonatal

Ethnicity – key points• Infant Mortality rates are higher in Pakistani and ‘Other’

populations.• IMR in the white population of Bradford is significantly

higher than that of white popn E&W

Cause of death

• Cause of death data is linked in to the master table from ONS deaths and is based on ICD10 coding.

• The categories of death used in this analysis are:– Congenital anomalies– Infections– Sudden infant deaths– Ante partum infections– Asphyxia, anoxia or trauma– Immaturity related conditions– External conditions– Other conditions– Other specific conditions

Cause of death – key points• Two main causes of death are Congenital Anomalies and

Immaturity Related Conditions.• The principle causes are most prevalent in the most

deprived areas.• Infant Mortality rates higher in Pakistani and ‘Other’

populations.

0

5

10

15

20

25

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

Congenitalanomalies

Immaturityrelated

conditions

Infections Externalconditions

Suddeninfant

deaths

Otherconditions

Otherspecific

conditions

Antepartuminfections

Asphyxia,anoxia ortrauma

Avera

ge a

nnual num

ber

of

Death

s

Actual Expected

Actual and Expected number of deaths, by cause, 1996-2002 and 2003-2009

• Calculated by multiplying the Bradford average yearly births by E&W rates.

• Most excess deaths seen for ‘congenital anomalies’ and ‘immaturity related conditions’.

Infant mortality rate by cause of death compared to E&W, 1996-2002 and 2003-2009

• Compared to Eng&Wales, there are significantly higher mortality rates due to ‘congenital anomalies’, ‘infections’ and ‘immaturity related conditions’ as well as other causes

0

1

2

3

4

5

6

7

8

9

10

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

1996-2002

2003-2009

Congenitalanomalies

Antepartuminfections

Immaturity relatedconditions

Asphyxia, anoxiaor trauma

External conditions Infections Other specif icconditions

Sudden infantdeaths

Other conditions

Rat

io o

f Bra

dfor

d to

E&

W r

ate

Infant mortality rate by cause and deprivation quintile, 2000-2009

• Higher rates of all main causes of death in the most deprived quintiles

0 2 4 6 8 10 12

5. Least deprived

4

3

2

1. Most deprived

De

priva

tion

qu

intil

e

Mortality rate per 1000 births

Antepartum infections Asphyxia, anoxia or trauma Congenital anomalies

Immaturity related conditions Infections Sudden infant deaths

External conditions Other conditions Other specific conditions

Infant mortality rate by cause and deprivation quintile, 2000-2009

1. Most deprived 2 3 4 5. Least deprived

Antepartum infections 0.2 0.1 0.2 0.1 0.3

Asphyxia, anoxia or trauma 0.5 0.7 0.2 0.4 0.5

Congenital anomalies 3.3 3.4 1.6 1.2 0.6

Immaturity related conditions 3.2 2.8 2.4 2.9 0.9

Infections 1.0 0.6 0.4 0.4 0.5

Sudden infant deaths 0.4 0.2 0.1 0.1 0.0

External conditions 0.5 0.4 0.1 0.0 0.1

Other conditions 1.7 1.1 0.6 0.2 0.5

Other specific conditions 0.6 0.4 0.2 0.0 0.2

All Causes 11.3 9.8 5.7 5.1 3.5

Deprivation quintileCause of Death

Cause of death by ethnicity, 2000-2009

• Higher infant mortality rate for Pakistani population largely attributable to higher rates of ‘Congenital anomalies’ and ‘Immaturity related conditions’.

Congenital AnomaliesImmaturity

0 2 4 6 8 10 12 14

Other

Pakistani 2nd gen

Pakistani 1st gen

White

Mortality rate per 1000 births

Other specific conditions

Other conditions

External conditions

Immaturity related conditions

Asphyxia, anoxia or trauma

Antepartum infections

Sudden infant deaths

Infections

Congenital anomalies

Cause of death by ethnicity, 2000-2009

OtherPakistani 2nd gen

Pakistani 1st gen

White OtherPakistani 2nd gen

Pakistani 1st gen

White

Congenital anomalies 2.6 5.2 5.1 1.3 1.4 5.8 3.0 0.9

Infections 0.2 0.0 1.1 0.6 0.2 0.7 1.0 0.9

Sudden infant deaths 0.4 0.4 0.0 0.1 0.2 0.0 0.0 0.5

Antepartum infections 0.2 0.2 0.1 0.2 0.0 0.0 0.1 0.3

Asphyxia, anoxia or trauma 0.4 0.7 0.9 0.4 0.2 0.4 0.4 0.5

Immaturity related conditions 3.4 2.8 2.6 1.6 2.2 4.4 3.8 2.4

External conditions 0.0 0.0 0.2 0.4 0.2 0.0 0.4 0.4

Other conditions 0.4 0.7 2.0 0.8 0.8 2.3 1.2 0.6

Other specific conditions 0.2 0.9 0.4 0.2 0.4 0.4 0.2 0.4

All Causes 7.9 10.9 12.3 5.5 5.5 14.0 10.0 6.7

Cause of Death

Infant Mortality Rate

Female Male

Cause of death – key pointsSince 2003 there is now a significant difference in the Bradford

IMR for ‘anoxia, asphyxia and trauma’.

Major excess cause of death for Pakistani mothers is congenital anomalies

• Persistent deprivation distribution for all aspects of infant mortality – LBW, Pre-term birth and major causes of death

• Rise in stillbirths, significantly so in full-term births over 15 years

• The pattern of risk of poor birth outcome by age of mother is different in Bradford to England and Wales – in Bradford women aged 24 – 34 remain at risk

• The numbers of deaths categorised as ‘other’ remains high

• Significant difference in the IMR from cause of death ‘Anoxia, asphyxia and trauma’ between Bradford and E&W (change from the BDIMC analysis)

• Change in mortality rates in the 1st and 2nd generation Pakistani mothers.

Key aspects