Recent Declines in Infant Mortality in the United States
Marian MacDorman, PhD and T.J. Mathews, MSDivision of Vital Statistics
National Center for Health Statistics
Vital Statistics Infant Mortality Data
• Based on birth and death certificates filed in state vital statistics offices, and transmitted to NCHS.
• National data files produced:
– Birth (natality) data set – 2011 preliminary and 2010 final currently available
– Main mortality file – 2011 preliminary and 2010 final currently available
– Linked birth/infant death data set
• Links birth and death certificate data for all infant deaths.
• Purpose: To use more detailed data from the birth certificate for infant mortality analysis.
• Currently available through 2008; 2009 expected by Jan. 2013
2000 2002 2004 2006 2008 2010 20110
1
2
3
4
5
6
7
8
4.62 4.54 4.67 4.63 4.52 4.54 4.46 4.42 4.29 4.18 4.05 4.04
2.27 2.30 2.28 2.22 2.25 2.32 2.22 2.33 2.32 2.21 2.10 2.01
Neonatal Postneonatal
Rate
per
1,0
00 li
ve b
irths
6.89 6.84
6.056.39
6.15
6.68 6.75 6.84 6.78 6.866.61
6.95
Infant, neonatal and postneonatal mortality rates, United States, 2000-2011
Source: NCHS linked birth/infant death data set, 2000-2009, mortality data set 2010, and preliminary mortality data set, 2011.
Percentage of preterm births: United States, 2000-2011
2000 2002 2004 2006 2008 2010 20110
2
4
6
8
10
12
14
3.4 3.4 3.5 3.5 3.6 3.6 3.7 3.6 3.6 3.5 3.5 3.4
8.1 8.4 8.6 8.8 8.9 9.1 9.1 9 8.8 8.66 8.49 8.3
<34 weeks 34-36 weeks
Per
cent
pre
term
12.3 12.211.6
12.3 12.5 12.7 12.8 12.711.6 11.9 12.1
Source: Births: Final data for 2010; Births, preliminary data for 2011.
11.9
Percent distribution of births by gestational age, US, 2006 and 2010
<34 34-36 37-38 39-41 42+0
10
20
30
40
50
60
70
3.79.1
28.9
52.6
5.73.5
8.5
26.9
55.6
5.7
2006 2010
Pe
rce
nt
SOURCE: National Vital Statistics System, NCHS, CDC.
Completed weeks of gestation
Infant mortality rate and percent of preterm births, US, 2000-2011
2000 2002 2004 2006 2008 2010 20110
1
2
3
4
5
6
7
8
0
2
4
6
8
10
12
6.89 6.84 6.95 6.84 6.78 6.86 6.68 6.75 6.61 6.39 6.15 6.05
Infant mortality rate % preterm
Infa
nt m
ort
alit
y ra
te p
er
1,0
00
live
birt
hs
Per
cen
t of
pre
term
bir
ths
Source: CDC/NCHS; national vital statistics system
Infant mortality rates by gestational age, US, 2008
Total <32 32-33 34-36 37-38 39-41 42+ 0
20
40
60
80
100
120
140
160
180
200
6.61
175.45
17.587.40 3.13 2.08 2.69
Ra
te p
er
1,0
00
live
birt
hs
Source: NCHS, linked birth/infant death data set.
Completed weeks of gestation
Percent of births and infant deaths by gestational age (weeks), US, 2008
<32Se-
ries153%
32-33Series1
4%
34-36Se-
ries110%
37+Se-
ries133%
Infant DeathsBirths 34-36
9%
37+87%
<322%
32-332%
Source: CDC/NCHS Linked birth/infant death data set, 2008
Components of infant mortalityThe overall infant mortality rate can be partitioned into two key components:
1. The distribution of births by gestational age;
2. Gestational age-specific infant mortality rates (i.e. the mortality rate for infants at a given gestational age)
Component 1 available through 2011; component 2 through 2008
Preliminary modeling suggests that both must have declined to yield the current infant mortality rate
Race/Ethnic Differences
0
2
4
6
8
10
12
1412.67
8.42
7.296.61
5.58 5.524.9 4.76 4.51
Ra
te p
er
1,0
00
live
bir
ths
Infant mortality rates by maternal race/ethnicity, US, 2008
Source: CDC/NCHS linked birth/infant death data set, 2008.
Non- American Puerto Total Mexican Non- Cuban Central Asian orHispanic Indian Rican Hispanic or South Pacific black white American Islander
Percent contribution of two components to race and ethnic differences in infant mortality rates, 2007
NHB/NHW infant mortality gap
PR/NHW infant mortality gap
AI/NHW infant mortality gap
0%
20%
40%
60%
80%
100%
78
100
24
22
0
76
Gestational age-specific infant mor-tality ratesDistribution of births by gestational age
Note: NHB=non-Hispanic black; NHW=non-Hispanic white; PR=Puerto Rican; AI=American IndianSource: CDC/NCHS; linked birth/infant death data set
Infant mortality rates by race/ethnicity, US, 2000, 2005 and 2011
Total Non-Hispanic white
Non-Hispanic black
Hispanic0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
6.915.71
14.11
5.646.87
5.73
14.28
5.806.055.05
11.96
5.27
2000 2005 2011
Source: Data from the vital statistics mortality file. Note: Infant mortality rates by race and Hispanic origin are more accurate from the linked birth/infant death data set.
Percent of preterm births by maternal race/ethnicity, US, 2000, 2006, 2011
Total Non-Hispanic white
non-Hispanic black Hispanic0
2
4
6
8
10
12
14
16
18
20
11.610.4
17.4
11.2
12.811.7
18.5
12.211.710.5
16.8
11.7
2000 2006 2011
Trends in Leading Causes
Of Infant Death
Infant mortality rates for the five leading causes of infant death in 2011: US, 2000, 2005, and 2011
0
20
40
60
80
100
120
140
160141.5
108.3
62.2
34.6
21.7
134.2
113.9
53.942.9
26.2
126.1
104.1
43.3 39.9
27.5
2000 2005 2011
Rate
per
100
,000
live
birt
hs
Source: NCHS, mortality data set. 2011 data are ore preliminary.
State Differences
MT
WY
ID
WA
OR
NV
UT
CA
AZ
ND
SD
NE
CO
NM
TX
OK
KS
AR
LA
MO
IA
MN
WI
IL IN
KY
TN
MS AL GA
FL
SC
NC
VAWV
OH
MI
NY
PA
MD
DE
NJ
CT RI
MA
ME
VT
NH
AK
HI
DC
Infant mortality rates by State, 2010
Source: National Vital Statistics System, NCHS, CDC
5.00 to 5.99
Less than 5.00
6.00 to 6.99
7.00 to 7.99
More than 8.00
U.S. rate = 6.15
MT
WY
ID
WA
OR
NV
UT
CA
AZ
ND
SD
NE
CO
NM
TX
OK
KS
AR
LA
MO
IA
MN
WI
IL IN
KY
TN
MS AL GA
FL
SC
NC
VAWV
OH
MI
NY
PA
MD
DE
NJ
CT RI
MA
ME
VT
NH
AK
HI
DC
Decline in infant mortality rates by state, 2005-2010
Source: National Vital Statistics System, NCHS, CDC
No significant change
Statistically significant decline of <20%
Statistically significant decline of 20% or more
U.S. change = -10.5
Understanding the Recent Decline in Preterm Birth
Understanding the Recent Decline in Preterm Birth
Decline in preterm births from 2006-2010 appears to be widespread. Declines in preterm rates for most/all: - maternal race/ethnic groups - maternal age groups - states - among both single and multiple births
Some factors to consider in changes to overall rate: - Recent decline in teen births (who have higher preterm rates)- Leveling out of multiple birth rates- Changes in obstetrical management of pregnancy
Components of preterm birth
“Indicated” preterm birth30-35%
PROM 25-30%
Spontaneous preterm labor40-45%
Source: Goldenberg et al. Lancet, 2008.
Percent preterm for cesarean, induced vaginal, and non-induced vaginal births: US, 2000, 2006, and 2010
Cesarean births Induced Noninduced0
2
4
6
8
10
12
14
16
18
20
17.1
7.7
10.6
17.8
7.7
11.6
16.7
6.8
10.7
2000 2006 2010
Vaginal births
International Comparisons
Infant mortality rates, OECD countries, 2009
United StatesSlovak Republic
PolandNew Zealand
HungaryUnited Kingdom
AustraliaSwitzerland
FranceItaly
AustriaIsrael
NetherlandsPortugal
GermanyBelgium
IrelandRepublic of Korea
SpainDenmark
GreeceNorway
Czech RepublicFinlandSweden
JapanIceland
0 1 2 3 4 5 6 7
6.45.7
5.65.2
5.14.6
4.34.3
3.93.9
3.83.83.8
3.63.5
3.43.23.23.2
3.13.13.1
2.92.6
2.52.4
1.8
Rate per 1,000 live birthsSource: Health, United States, 2012. OECD=Organization for Economic Cooperation and Development.
Percentage of preterm births, United States and selected European countries, 2004
United StatesAustria
GermanyHungary
SpainScotland
England and WalesNetherlands
NorwayCzech Republic
DenmarkItaly
PolandPortugal
Northern IrelandFrance
SlovakiaSwedenGreeceFinlandIreland
0 2 4 6 8 10 12 14
12.411.4
8.98.6
8.07.67.57.4
7.17.06.96.86.86.8
6.66.36.36.3
6.05.65.5
Note: Excludes births at <22 weeks of gestation to promote comparability between countries. Preterm births are those from 22 to 36 weeks of gestation. Source: NCHS linked birth/infant death data set (for US data), and European Perinatal Health Report (for European data).
Conclusions- After a plateau from 2000-2005, the US infant mortality rate
declined 12% from 2005 to 2011.
- After more than two decades of increase, there was a 9% decrease in the preterm birth rate from 2006-2011.
- From 2005-2011, infant mortality declined most rapidly for non-Hispanic black women (-16%), followed by non-Hispanic white (-12%) and Hispanic women (-9%), based on mortality file data.
- Infant mortality declines were largest for states such as Louisiana, Georgia, the Carolinas and DC with large African-American populations and which previously had persistently high infant mortality rates.
- Provisional data from July 2011-June 2012 show a US infant mortality rate of 5.9, suggesting a continued downward trend from the rate of 6.05 in 2011.
Links to some recent reports
Infant mortality statistics from the 2008 linked birth/infant death data set: http://www.cdc.gov/nchs/data/nvsr/nvsr60/nvsr60_05.pdf
Deaths, preliminary data for 2011: http://www.cdc.gov/nchs/data/nvsr/nvsr61/nvsr61_06.pdf
Tables from Deaths, Final data for 2010:http://www.cdc.gov/nchs/data/dvs/deaths_2010_release.pdf
Births, preliminary data for 2011: http://www.cdc.gov/nchs/data/nvsr/nvsr61/nvsr61_05.pdf
Births: final data for 2010:http://www.cdc.gov/nchs/data/nvsr/nvsr61/nvsr61_01.pdf
Provisional monthly and 12 month ending number of deaths, live births and infant deaths and rates: United States, January 2011 to June 2012. http://www.cdc.gov/nchs/data/dvs/provisional_tables/Provisional_Table01_2012Jun.pdf
Contact information
Marian MacDorman 301-458-4356 [email protected]
T.J. [email protected]
Any questions?