INCIDENCE AND REPORTED CAUSES OF
STILLBIRTHS IN ARIZONA
Fifth Annual Report
November 2009

Prepared by:
Douglas Ritenour, MPH
Epidemiology Specialist II
150 N. 18th Avenue, Suite 320
Office of Assessment and Evaluation
Bureau of Women’s and Children’s Health
Division of Public Health Services
Arizona Department of Health Services

Leadership for a Healthy Arizona
Janice K. Brewer, Governor
State of Arizona
Will Humble, Interim Director
Arizona Department of Health Services

MISSION
Setting the standard for personal and community health through
direct care delivery, science, public policy and leadership.

Arizona Department of Health Services
Public Health Prevention Services
Bureau of Women’s and Children’s Health
Assessment and Evaluation Section
150 North 18th Avenue, Suite 320
Phoenix, Arizona 85007
(602) 364-1463

This publication can be made available in alternative format. Please contact the Child
Fatality Review Program at (602) 542-1875 (voice) or call 1-800-367-8939 (TDD).
Permission to quote from or reproduce materials from this publication is granted when
acknowledgment is made.

i

Contents
Page
Executive Summary.................................................................................................

1

Introduction………………………………………………………………………..
Background………………………………………………………………....
Methodology………………………………………………………………..
Arizona 2008……………………………………………………….............

2
2
2
2

Maternal Risk Markers…………………………………………………………..
Pregnancy History………………………………………………………….
Race/Ethnicity……………………………………………………………...
Maternal Age……………………………………………………………….
Maternal Education………………………………………………………...
Prenatal Care………………………………………………………….........
Behavioral Risk Markers…………………………………………………..

3
3
4
4
5
6
7

Characteristics of Stillbirths……………………………………………………..
County of Occurrence and Frequency of Autopsy…………………………
Reported Cause of Death……………………………………………….......

8
9
11

Data Quality……………………………………………………………………….
Case Inclusion................................................................................................
Quality of Data Fields....................................................................................

14
14
14

References................................................................................................................

17

ii

Tables

Page

1. Appendix A.........................................................................................................

15

2. Appendix B.........................................................................................................

16

iii

Figures

Page

1. Stillbirth Rates, 2003-2008.....................................................................................

3

2. Stillbirth Rates by Year and Race/Ethnicity, 2003-2008........................................

4

3. Stillbirth Rates by Maternal Age, 2008..................................................................

5

4. Stillbirth Rates by Level of Education, 2008.........................................................

5

5. Women Entering Prenatal Care by Trimester 2008...............................................

6

6. Women Reporting Cigarette or Alcohol Use during Pregnancy, 2008..................

7

7. Stillbirth by Gestational Age, 2008........................................................................

8

8. Reported Weight of Stillbirths, 2008 .....................................................................

8

9. Stillbirths Autopsy by Urban and Rural Counties, 2008........................................

9

10. Stillbirths Autopsied by Reported Weight, 2008.................................................

10

11. Autopsies Used in Determining Cause of Death among Stillbirths Receiving
an Autopsy, 2008..................................................................................................

11

12. Stillbirths with Valid Cause of Death, 2008 ........................................................

12

13. Specific Causes of Stillbirth, 2008........................................................................

13

14. Top Three Causes of Stillbirth by Gestational Age, 2008.....................................

13

iv

Executive Summary
____________________________________________________________
This report completes the annual requirement set forth by the Arizona State Legislature to
present the incidence and causes of stillbirth. Fetal death certificate data were utilized to
draw conclusions about the risks of stillbirth by women’s age, race, education, initiation of
prenatal care, and tobacco/alcohol use during pregnancy. The report also examined the
prevalence and causes of stillbirth, and the use of autopsy by region and county.
The findings of this report indicate that the incidence of stillbirth remained unchanged over
the past five years. The 2008 rate of stillbirth in Arizona (5.5 per 1,000 live births and fetal
deaths) is lower than the last reported U.S. rate in 2005 (6.2).1 However, unless there is a
significant decline in the rate of stillbirths in 2009, Arizona will not meet the Healthy People
2010 objective of 4.1 stillbirths per 1,000 live births plus stillbirths.
This report also demonstrates that disparities in the rate of stillbirths persist. African
American women are significantly more likely to experience a stillbirth compared to all
other races. The largest preventable risk behavior for stillbirth, tobacco use during
pregnancy, was more commonly found in women delivering a stillbirth compared to
mothers delivering a live birth. Risk markers such as limited education, pregnancy beyond
35 years of age, and late initiation of prenatal care remain significantly associated with
stillbirth in Arizona. Maricopa and Pima Counties accounted for the vast majority of
stillbirths (77 percent) in 2008, and the rate of stillbirth in Arizona’s urban counties (5.5 per
1,000 live births plus stillbirths) was greater than the rate in rural counties (4.9) (see
Appendix A).
Length of gestation and delivery weight were associated with the incidence and causes of
stillbirth. The majority of stillbirths weighed less than 1,500 grams (59 percent) and were
more likely to occur early term (46 percent) rather than at term (17 percent). Malformations
were the reported as the leading cause of death for early term stillbirths, while cord
problems were the leading cause of death in term/late term stillbirths. Autopsy was more
often conducted on later term stillbirths with greater delivery weight. Although autopsy is
recognized as the most useful procedure in determining cause of death, only 10 percent of
stillbirths delivered in 2008 underwent the procedure. This report did not examine the
medical, legal or infrastructure barriers to increasing the autopsy rate for stillbirths.
Arizona’s continued use of the outdated 1989 U.S. Standard Fetal Death Certificate
restricts a more profound examination of the incidence and causes of stillbirth.

1

INTRODUCTION
Background
As required by Arizona law (ARS 36-2291), the first annual report on the Incidence and
Reported Causes of Stillbirths was completed in May of 2005 using data from the 2003
fetal death cohort. Because of the relatively small number of cases, the second annual
report examined data from 2000 through 2004 and the fourth annual report also used a
five-year cohort of fetal deaths from 2003 through 2007. The Fifth Annual report uses a
one year cohort of fetal deaths from 2008 for most analyses.
Methodology
Arizona electronic fetal death certificate data for deaths occurring between the1st of
January, 2008 and the 31st of December 2008 are summarized in this report. To conduct
the analyses, an electronic file was created with fetal death and live birth data from tables
generated by the Health Status and Vital Statistics Section of the Bureau of Public Health
Statistics within the Arizona Department of Health Services. These files contain data on
stillbirths which are reported to occur at or after 20 weeks of gestation, and if gestational
age is unknown, the deaths of fetuses of at least 350 grams. In this report, the cohort was
limited to those cases that reported residence in Arizona.
This report focuses on the incidence of stillbirth, maternal risk markers/risk factors for
stillbirth, and reported causes of stillbirths. The number of incident deaths and stillbirth
rates are useful when looking at trends over time, comparing one geographic population to
another and comparing subgroups within a population. In this report, live births from the
birth certificate database and fetal deaths (excluding induced abortions) are combined as
an estimate of the total pregnancies among Arizona residents that are at risk for a fetal
loss. Stillbirth rates are expressed as the number of deaths per 1,000 live births and fetal
deaths. Stillbirth rates are presented in this report by race and ethnicity, maternal age, and
education level. Two behavioral risk markers, smoking and alcohol consumption, are
analyzed in this report. The prevalence of autopsy is examined by weight, age, and
geographic region of stillbirths. Finally, the reported causes of stillbirth are addressed,
limitations of these data are considered, and input from national and international experts
is presented.
Arizona 2008
As per the Arizona Vital Records Fetal Death Certificate database, there were a total of
544 stillbirths reported to have occurred at 20 weeks or more gestation (or if gestational
age was unknown, the deaths of fetuses of at least 350 grams) during the 1st of January
2008 through the 31st of December 2008. Figure 1 shows that the stillbirth rate ranged
from a high of 5.9 per 1,000 live births and fetal deaths in 2003 to a low of 5.3 in 2006. The
2008 rate is not significantly different from the baseline rate in 2003. * The stillbirth rate in
Arizona for the combined six-year period was 5.5 per 1,000 live births and fetal deaths,
which was lower than the U.S. rate of 6.2 per 1,000 for 2005 (see Appendix B).1
Nevertheless, the stillbirth rate in Arizona for 2008 remains 34 percent greater than the
Healthy People 2010 objective of 4.1 per 1,000 live births and fetal deaths.2 If Arizona had

*

P =.28 (CI: -0.28 - 1.10)

2

met the Healthy People 2010 standard from 2003 to 2008, approximately 850 stillbirths
would have been averted.
Figure 1. Stillbirth Rates (per 1,000 live births + fetal deaths)
Arizona 2003-2008
(n= 3,246)
10.0

Arizona
Healthy People 2010 Goal

9.0
8.0
Rate per 1,000

7.0

5.9
5.4

6.0

5.5

5.3

5.6

5.5

5.0
4.1

4.0
3.0
2.0
1.0
0.0
2003 (n=539)

2004 (n=505)

2005 (n=532)

2006 (n=543)

2007 (n=583)

2008 (n=544)

Year

MATERNAL RISK MARKERS
Few hypothesized “risk factors” have been causally linked to stillbirth.3 A more appropriate
term to describe the many associations with stillbirth is maternal risk marker. These
physical, behavioral and environmental markers are used as proxies for unavailable causal
data, or as yet to be discovered “risk factors” that actually cause stillbirth.
Pregnancy History
Previous history of stillbirth has been associated with a higher risk for future stillbirth.4
Twenty-seven percent of women with valid data in the 2008 stillbirth cohort reported
between one and six previous spontaneous or induced terminations of pregnancy. It is
unknown what proportion of these “terminations” met the definition of stillbirth
(spontaneous termination of pregnancy at 20 or more weeks gestation). In addition, it is
possible that some women who delivered a stillbirth in 2008 also delivered a live infant and
are part of the 2008 live birth cohort. Therefore, determining risk for stillbirth based on
previous history of stillbirth is not possible in this report.
Multiple gestations have also been associated with stillbirth. Approximately 10 percent of
all stillbirths in the United States are delivered by women carrying multiple fetuses. The
risk for stillbirth increases with the number of fetuses carried during pregnancy.3 For
multiparous women residing in Arizona, the rate of stillbirth was 14.4 per 1,000 live multiple
births and fetal deaths. The rate of stillbirth among singleton pregnancies (5.2 per 1,000
live singleton births and fetal deaths) was significantly less than for multiple pregnancies. *

*

P<0.0001(CI: 6.50 - 11.90)

3

Although assisted reproductive technology (ART) has been associated with both multiple
gestation and stillbirth, no data exist for women using ART in the fetal or birth certificate
databases. There is no consensus about whether multiple fetuses have additional risk
because they were conceived with ART.3
Race/Ethnicity
Figure 2 shows the stillbirth rates by stillbirths with reported race/ethnicity for the 2003
through 2008 time period in Arizona. The stillbirth rate was lowest for White, non-Hispanic
women (4.7 per 1,000 live births and fetal deaths) and highest for Black or African
American women (10.1 per 1,000 live births and fetal deaths) in 2008. A significant
disparity in stillbirth rates persisted between Black or African American women and other
racial/ethnic groups in 2008.* Pregnant Black or African American women had 1.84 times
the risk of having a stillbirth as non-African American women. This disparity is apparent in
stillbirth rates across the United States (Appendix B).5 Healthy People 2010 calls for a
significant reduction in the disparity of stillbirth rates across all racial and ethnic groups.3

16.0

Figure 2. Stillbirth Rates (per 1,000 live births+fetal deaths) by Race/Ethnicity
Arizona 2003-2008
(n= 3,231)a

Rate per 1,000

14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
2003

2004

2005
a

White, non-Hispanic
Hispanic or Latino
Asian or Pacific Islander

2006

2007

2008

Year
excludes missing cases

Black or African American
American Indian or Alaskan Native

Maternal Age
Age is a risk marker for stillbirth. Maternal age is used as a proxy measure of unknown
and unmeasured biological changes that are causal for stillbirth.3 Figure 3 indicates the
relationship between reported maternal age and stillbirth. It is evident from figure 3 that the
highest risks of stillbirth were for adolescent and older women. However, in 2008 women
under 20 years of age did not assume a statistically greater risk for stillbirth than women
20 to 34 years old.** The risk of experiencing a stillbirth also increases for women 35 years
of age and older. For these women, the risk for stillbirth was 1.3 times as great as women
in their twenties. ***
*

P<0.0001 (CI: 1.8 - 7.8)
P=.240 (CI: -0.63 - 2.3)
***
P=0.017 (CI: 0.15 - 3.25)
**

4

Rate per 1,000

20.0

Figure 3. Stillbirth Rates (per 1,000 live births + fetal deaths) by Maternal Age
Arizona 2008
a
(n= 542)

12.3b
b

9.3

10.0

6.2b

5.3b

6.2
5.0

5.0

5.2

20 to 24
years
(n=132)

25 to 29
years
(n=141)

30 to 34
years
(n=113)

0.0

Less than
15 years
(n=2)

15 to 17
years
(n=22)

18 to 19
years
(n=49)

35 to 39
years
(n=63)

40 years
and older
(n=20)

a

excludes unknown and missing cases.
interpret rate with caution due to small sample size.

b

Maternal Education
Figure 4 shows the stillbirth rates by reported level of maternal education. High school
education or less is a risk marker for stillbirth that may serve as a proxy measure for other
causal risk factors, such as elevated stress associated with lower socio-economic status.
Women with 12 years of education or less (6.2 per 1,000 births and fetal deaths)
experienced significantly higher rates of stillbirths than women with 13 years or more of
education (4.4 per 1,000).*

Figure 4. Stillbirth Rates (per 1,000 live births + fetal deaths)
by Level of Education, Arizona 2008
(n=537)a

Rate per 1,000

10.0

6.2
4.4

5.0

0.0
12 Years or less
(n=350)

13 Years or more
(n=187)

a

excludes unknown and missing cases

*

P<0.0001(CI: 0.89 - 2.70)

5

Prenatal Care
Determining the adequacy of prenatal care in stillbirths through a review of fetal
death certificate data is complicated. Birth certificate data and fetal death certificate data
do not contain any information on the quality or content of prenatal care. Methodologies for
determining adequacy of prenatal care in live births, such as the Kotelchuck Index 6, look
at both the timing of entry into care and the number of prenatal visits received. “Adequacy
of care”, in terms of the number of expected visits, may be different for women at risk of
experiencing a stillbirth. If a woman enters prenatal care early and a risk factor is identified,
she may require more prenatal care visits than a woman without an identified risk factor.
Conversely, women who receive no prenatal care or enter prenatal care late in pregnancy
may be at higher risk for delivering a stillborn infant because a preventable risk factor is
not identified and addressed early enough to positively affect the health of the fetus.
Therefore, interpreting adequacy of prenatal care measures for fetal deaths is not
presented in this report.
Figure 5 compares entry into prenatal care for women experiencing stillbirths and entry
into prenatal care for women giving birth to live infants in 2008. Delivery status (stillbirth or
live birth) was significantly associated with first trimester prenatal care.* In addition, women
delivering a stillbirth were more likely to delay entry into prenatal care until the third
trimester.
Figure 5. Women Entering Prenatal Care by Trimester
Arizona 2008a
100.0%
Stillbirths (n=534)
Live Births (n=99,108)

75.3% 79.4%

50.0%

16.1%

15.2%
1.9% 3.6%

6.7%
1.8%

0.0%
1st Trimester

2nd Trimester

3rd Trimester

No Prenatal Care

a

excludes unknown and missing cases

*

Chi-square 5.64 (1), P=0.018

6

Behavioral Risk Markers
Cigarette use is the largest preventable cause of stillbirth. Cessation of smoking during the
first trimester has been shown to lower the risk of stillbirth to equivalent rates found in nonsmoking women.3 The consumption of alcohol during pregnancy has found to be
associated with stillbirth in some, but not all studies . As with tobacco use, the
consumption of alcohol may play a larger role in stillbirth later in pregnancy.3
Cigarette and alcohol use during pregnancy are recorded on the fetal death certificate.
This analysis is restricted to women with known responses to the questions of smoking or
drinking in the 2008 stillbirth cohort (n= 520 smoking responses; n= 517 drinking
responses) and live birth cohort (n= 98,973 smoking responses; n= 98,836 drinking
responses). The Arizona fetal death certificate does not contain information about cigarette
or alcohol use by trimester. Figure 6 shows the percentage of women who reported
smoking cigarettes or drinking alcohol during pregnancy for the 2008 stillbirth and live birth
cohorts.
Figure 6. Women Reporting Cigarette or Alcohol Use during Pregnancy
by Birth Status, Arizona 2008
50.0%
Smoking

Alcohol

40.0%
30.0%
20.0%
10.0%

7.9%
4.9%
1.6%

<1%

0.0%
Delivered Stillbirth

Delivered Live Birth

Approximately eight percent of women who had a stillbirth reported smoking and 1.6
percent reported drinking while pregnant. Only 4.9 percent of women delivering a live birth
reported smoking and less than one percent reported drinking alcohol during pregnancy.
Within this sample, the rate of stillbirth among women who reported smoking during
pregnancy (8.4 per 1,000 live births + stillbirths) was significantly greater than the rate of
stillbirth among non-smokers (5.1 per 1,000).* The rate of stillbirth for women who reported
drinking alcohol during pregnancy is not presented because of limited response size.
Response bias due to the stigma of smoking and drinking during pregnancy likely resulted
in underreporting of these two behaviors across both the stillbirth and live birth cohorts. If
the behavior was stopped early in pregnancy, recall bias may also limit the reliability of
these data. When Arizona adopts the U.S. Revised Fetal Death and Birth Certificates,
information about alcohol use during pregnancy will no longer be collected.
*

P<0.002 (CI: 0.57-5.79)

7

CHARACTERISTICS OF STILLBIRTHS
Cases in the fetal death certificates are defined by gestational age, and when age is not
available, delivery weight of at least 350 grams is used. Figure 7 shows the breakdown of
stillbirths by reported early, late, full term, and post-term gestational ages.7 Similar to
national statistics,3 46 percent of stillbirths in Arizona occurred prior to 28 weeks gestation
and 17.7 percent were ‘at term’. Although gestational age is determined by physician’s
estimate (clinical estimate) and not reported date of last menstrual period, reliability and
validity issues persist.8

Figure 7. Stillbirths by Gestational Age
a
Arizona 2008 (n= 543)
100.0%

50.0%

46.0%

35.5%
17.7%
1%

0.0%

20 through 27 weeks 28 through 36 weeks 37 through 40 weeks 41 weeks or more
(n=250)
(n=193)
(n=96)
(n=4)
a

excludes unknown and missing cases

Figure 8 shows the reported weight of stillbirths from the 2008 cohort.
Figure 8. Delivery Weight of Stillbirths
Arizona 2008
(n=544)
4,500 gram s or m ore
1.1% (n=6)
2,500 to 4,499 gram s
19.7% (n=107)

1,500 to 2,499 gram s
18.8% (n=102)

unknow n
2.6% (n=14)
less than 350 gram s
17.1% (n=93)

350 to 1,499 gram s
40.8% (n=222)

8

It is evident from Figure 8 that approximately 41 percent of stillbirths delivered in 2008
were reported to weigh between 350 to 1,499 grams, and 19 percent weighed between
1,500 and 2,499 grams. Another 17 percent were reported to weigh less than 350 grams
and 14 cases were missing data for birth weight. Most fetuses that survive to 20 weeks
gestation weigh over 350 grams.9 Therefore, it is possible that some of the reported
weights of less than 350 grams were either data errors or misclassified cases of
miscarriage.

County of Occurrence and Frequency of Autopsy
Although the majority of stillbirths in 2008 continued to occur among female residents of
urban counties, rates of stillbirth varied more widely in rural counties (1.4 to 8.5 per 1,000)
compared to urban counties (5.3 to 5.7) due to the relatively small size of rural populations
(appendix B). In 2008, 64 percent of those stillbirths were delivered by residents of
Maricopa County (n=350), 13 percent in Pima county (n=73), and the remainder of
stillbirths with known maternal residence occurred in 12 other counties (n=120).
Fetal autopsies are the most useful diagnostic procedure for information on the cause of
death.3,10 However, only 10 percent (n=51) of stillbirths with complete data in 2008
received an autopsy. The proportion of stillbirths receiving an autopsy has decreased from
a high of 16.4 percent in 2004. Additionally, the quality of data declined each year over the
reported autopsy field. Fewer than one percent of cases were coded as “unknown” in
2003, but 7.5 percent coded as “unknown” in 2008.
Figure 10 shows the proportion of stillbirths delivered in urban and rural counties that
received an autopsy. The percentage of “unknown” autopsied cases in rural counties
makes it impossible to determine if there was a significant urban/rural difference. Although
the proportion of stillbirths autopsied was greater in Maricopa County compared to Pima
County (9.1 percent compared to 7.5 percent), the difference was not significant. *
Figure 9. Stillbirths Autopsied by Urban and Rural Counties
Arizona 2008 (n=544)
100.0%
87.2%

Autopsied

Not Autopsied

45.3%

50.0%

9.2%

U nknown

43.4%

11.3%
3.7%

0.0%
Urban Counties (n=491)

*

Rural Counties (n=53)

Chi-square .21 (1), P=.65

9

The proportion of autopsies was also analyzed by race, ethnicity, gestational age, and
reported weight of the fetus. In terms of race and ethnicity, the percentage of stillbirths
delivered by non-Hispanic women that received an autopsy was 9.3 percent compared to
11 percent of stillbirths delivered by Hispanic women. The proportions of stillbirths
autopsied for White (7.6 percent), African American (11.4 percent), and Asian (10.5
percent) women were all higher than for stillbirths autopsied for American Indian women
(4.7 percent). However, the high percentage of ‘unknown autopsy status’ among American
Indian stillbirths (27.7 percent) limits the interpretation of the disparity.
Although nearly half of all stillbirths were delivered prior to 28 weeks gestation, only 7.8
percent of these very early term stillbirths received an autopsy. There was no significant
difference in autopsy rates between stillbirths occurring at or after 28 weeks gestation
(11.3 percent) and those occurring very early term. *
Figure 10 shows the percentage of stillbirths that were autopsied by reported gestational
weight. Of stillbirths that received an autopsy, the majority were either very low weight (350
to 1,499 grams) or normal weight (2,500 to 4,499 grams). Only 5 percent of stillbirths
weighing 1,500 to 2,400 grams received an autopsy.

Figure 10. Stillbirths Autopsied by Reported Weight
Arizona 2008 (n=530)*
50.0%
33.3%
25.0%

16.8%
9.5%
4.9%

4.3%
0.0%
< 349
grams (n=4)

350 to 1,499
grams (n=21)

1,500 to 2,499
grams (n=5)

2,500 to 4,499
grams (n=18)

4,500 or more
grams (n=2)

*excludes cases with unknown or missing weight

*

Chi-square 2.68 (1) P=0.10

10

Figure 11 shows the percentage of autopsies that were actually used to determine the
cause of death among stillbirths that received an autopsy. Although autopsy is considered
the most useful procedure in determining the cause of stillbirth,3,4 the procedure was rarely
utilized to ascertain the cause of fetal demise in Arizona.
Figure 11. Percent of Autopsies Used in Determining Cause of Death among
Stillbirths Receiving an Autopsy
Arizona 2008 (n=51)*
100.0%

58.8%
50.0%

23.5%

17.7%
0.0%
Autopsy Used (n=9)

Autopsy Not Used (n=30)

Unknown (n=12)

*total number of stillbirths autopsied

Reported Cause of Death
Most conditions that have been linked to stillbirth can be classified as associations rather
than unequivocal causes.3 As reported in the first Incidence and Reported Causes of
Stillbirth Report (2005), the cause of stillbirth often remains unknown, even when a
concerted effort is made to determine the cause of death. In Arizona, three causes of
death can be entered onto the fetal death certificate – a primary cause of death and two
contributing factors. Since 2000, the cause of death has been coded using ICD-10 codes
in Arizona.
Coding for fetal death certificates is completed by Arizona Department of Health Services
Vital Records staff. The staff person responsible for coding fetal deaths reviews a hard
copy of the fetal death certificate and, using all three fields on the death certificate, makes
a determination of the most appropriate ICD-10 code. In 2008 there were 58 distinct ICD10 codes used to classify cause of death in the fetal death certificate data. The ICD-10
codes and their associated descriptions were reclassified into categories based on their
similarities and potential prevention efforts. *

*

ICD-10 codes were reclassified according to a matrix created by Dr. Mike Clement of the Arizona Perinatal
Trust in 2006. The use of other classification systems, such as Gardosi’s ReCoDe4 , was not possible due to
the absence of key variables in the 1989 U.S. Standard Fetal Death Certificate.

11

Figure 12 shows causes of stillbirths for the 2008 reporting period. As is true in many
studies on the causes of stillbirths3, the cause of death was unknown in 44 percent of
stillbirths for this time period. The lack of a definitive cause of death is often the result of
insufficient medical science regarding the etiology of stillbirth.* Additionally, data errors are
common across this field as 10 percent of the stillbirths had an inappropriate ICD-10 code,
four percent of the stillbirths had an invalid ICD-10 code, and three percent of the stillbirths
did not have an ICD-10 code listed under cause of death. The remaining 38 percent of
fetal deaths had ICD-10 codes indicating a valid and specific cause of deaths.

Figure 12. Percent of Stillbirths with Valid Cause of Death
Arizona 2008 (n=544)

Inappropriate ICD 10
(n=52)
10%

Valid and Specific
Cause (n=208)
38%

Other residual No ICD-10 Code
(n=16)
causes (n=7)
3%
1%
Invalid ICD-10 (n=22)
4%

Recoded as
Unknown (n=239)
44%

_______________________
*As per correspondence with Donna Hoyert, PhD, Division of Vital Statistics, NCHS, CDC, on November
25th, 2008.

12

Of the stillbirths with a known and specific cause of death (Figure 13), the most common
causes were malformations (30 percent), placental disorders (27 percent), and cord
problems (26 percent). None of the other recoded causes of death accounted for more
than five percent of stillbirths with valid ICD-10 data.
Figure 14. Spe cific a nd Va lid Ca use s of Stillbirth
Arizona 2008 (n=208)

Malformations
Placental Disorders
Cord problems
Hydrops Fetalis or Isoimmunization
Hypertension
C ardiovascular
Inflamation/Infection
IUGR
Hypoxia
Maternal or Fetal Blood Loss
0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

Pe rce nt

Figure 14 shows the top three reported causes of death by early term (less than 28 weeks)
and term/post-term (37 weeks or more) gestational age categories.
Figure 15. Top Thre e Ca uses of De a th by Ge sta tiona l Age of Stillbirth
Arzona 2008 (n=132)
75.0%

Cord problems
Malformation
Placental disorders

percent

50.0%

25.0%

0.0%
Le ss tha n 28 W ee ks (n=86)

37 W e eks or More (n=46)

*includes only cases with valid ICD 10 cause of death

13

Forty-six percent of stillbirths delivered at term or late term had a specific cause of death,
while only 35 percent delivered at less than 28 weeks had a valid cause of death.* The
most common causes of death were cord problems, malformations and placental disorders
for both age categories. For stillbirths delivered at term or late term, cord problems (39
percent) accounted for the greatest proportion of deaths, while malformation (42 percent)
was the most common cause of death for early term stillbirths.

DATA QUALITY
The analysis for the 2009 Incidence and Reported Causes of Stillbirth in Arizona consisted
of a review of frequencies of selected variables to determine the percentage of cases with
out-of-range, invalid, and missing values. Fields were chosen for this analysis based on
the likelihood that they would be used in an analysis of stillbirths. In addition to reviewing
frequencies as described above, the data were reviewed to determine if the cases included
in the fetal death files were appropriate for an analysis of fetal deaths.

Case Inclusion
ARS 36-2291 stipulates that a report on the incidences of stillborn infants and the reported
causes of deaths will be produced each year. Fetal weights and reported gestational age
were reviewed to determine if all records included in these files would be appropriate for a
report on the incidence and causes of stillbirths. Of the 544 cases reported in these files,
only one record did not have data in the field for reported gestational age. This record had
a weight of at least 350 grams indicating that the fetus was likely of an appropriate
gestational age for inclusion in this report. The remaining 543 cases had gestational ages
of 20 weeks or more according to clinical estimates. Both clinical and calculated estimates
of gestational age are subject to reliability issues.8 Calculation of gestational age by
reported last menstrual period is complicated by missing and unreliable data over 11
percent of cases. Nevertheless, when using date of last menses to measure gestational
age, approximately four percent (n=23) of stillbirths were less than 20 weeks old and over
one-third these cases (n=9) also had reported delivery weights under 350 grams. These
cases would not be included in this report had last menses been used instead of clinical
estimate to determine gestational age.
Gestational age is the primary criteria used to determine case inclusion in this report.
However, the reported weight of all cases was also reviewed to determine whether or not
the case was appropriate for inclusion in an analysis of incidence and reported causes of
stillbirth. Seventeen percent (n=93) of stillbirths in the data set were reported to weigh less
than 350 grams and less than three percent (n=14) had missing birth weight. One delivery
facility was responsible for 19 percent of the missing data and cases with birth weight
under 350 grams, while accounting for 13 percent of all stillbirth deliveries.

__________________
Chi-square 3.61 (1) P=0.057

14

Quality of Data Fields
The quality of data was examined across all selected variables used in this report. When
more than five percent of data was missing, this was cited in the report. Additional
variables that would have been useful for the analysis of the causes of stillbirth include the
amount of cigarettes smoked per week, self-reported exposure to second hand smoke, the
number of alcoholic drinks consumed per day by trimester, and the weight and height (or
calculated BMI) of the mother at first prenatal care visit. Although the prevalence of obesity
has increased among reproductive aged women in Arizona11 and has been demonstrated
as a risk factor for stillbirth,3,4,5 neither maternal baseline weight nor height is collected for
the Arizona fetal death certificate. These missing variables limit the strength of this report.
The revised 2003 U.S. Standard Fetal Death Certificate (see http://www.azdhs.gov
/plan/cert/ pdf/fetal.pdf ) includes data fields for BMI, pre-pregnancy weight, and
trimester/frequency of cigarette use. If adopted in Arizona, the revised fetal death
certificate would bolster future analyses of the risks for stillbirth. For instance, Gardosi’s
classification of stillbirth by relevant condition of death (ReCoDe) utilizes mother’s first
trimester BMI as a covariate to determine customized fetal delivery weight percentiles. If
delivery weight for gestational age is extremely low (< 10th percentile) and no valid cause
of death is noted, then the fetal death is reclassified as due to fetal growth restriction. Use
of the ReCoDe classification system has resulted in the valid coding of up to 85 percent of
fetal deaths.12,13

15

Appendix A
Total Number of Stillbirths*

Rate of Stillbirths**

2003 2004 2005 2006 2007 2008

2003 2004 2005 2006 2007 2008

5.9
5.4
5.5
5.3
5.6
5.5
ARIZONA 539 505 532 543 583 544
8
5
7
4
9
8
6.4
3.7
5.4
3.4
7.7
6.6
Apache
15
10
14
12
13
7
8.5
5.5
7.9
6.6
7.0
3.9
Cochise
14
7
9
14
9
7
7.2
3.4
4.3
6.8
4.2
3.5
Coconino
1
2
3
11
4
6
1.4
3.0
4.6 16.5
5.7
8.5
Gila
8
2
2
2
0
5
18.1
4.4
4.4
3.7
0.0
7.7
Graham
2
1
1
0
0
1
22.5
9.6 10.0
0.0
0.0
7.6
Greenlee
5.6
5.6
5.3
5.3
5.4
5.6
Maricopa 330 339 330 351 360 350
10
11
19
15
17
9
4.7
5.0
8.4
6.1
6.9
3.9
Mohave
9
12
15
13
15
15
5.2
6.7
7.8
6.9
7.4
7.7
Navajo
80
54
68
79
88
73
6.2
4.1
5.2
5.7
6.3
5.4
Pima
16
14
21
17
39
33
5.5
4.5
5.7
3.8
7.3
5.7
Pinal
1
4
5
3
0
6
1.3
4.9
6.4
4.0
0.0
7.5
Santa
Cruz
14
15
7
10
14
3
7.5
7.4
3.3
4.2
5.7
1.4
Yavapai
30
25
30
12
14
18
9.3
7.5
9.0
3.6
4.3
5.3
Yuma
1
4
0
0
0
2
4.6 17.1
0.0
0.0
0.0
8.1
La Paz
0
0
0
0
0
1
NA
NA
NA
NA
NA
NA
Unknown
*Includes spontaneous terminations of pregnancy at 20 or more weeks of gestation (or if gestational
age is unknown, the deaths of fetuses of at least 350 grams in weight). Excludes induced
terminations of pregnancy.
**

Per 1,000 live births plus reportable fetal deaths.

Note: Urban counties include Maricopa, Pima, Pinal and Yuma. All other counties are considered
rural.
This table is adapted from Table 5C-3 in the 2008 Arizona Health Status and Vital Statistics.

16

Appendix B

Stillbirths: Arizona and the U.S.
Arizona 2008

U.S. 2005*

Total number

544

25,894

Total rate (per 1,000 live births and fetal deaths)

5.5

6.2

Black or African American

10.1

11.1

American Indian or Alaskan Native

7.3

6.2

Asian or Pacific Islander

5.5

4.8

Hispanic or Latina

5.4

5.4

non-Hispanic White

4.7

4.8

Triplet or more

16.9**

27.2

Twin

14.3

16.1

Singleton

5.2

5.9

12.3**

12.2

15 thru 19 years old

5.9

7.5

20 thru 24 years old

5.0

5.9

25 thru 29 years old

5.0

5.5

30 thru 34 years old

5.2

5.8

35 thru 39 years old

6.2

7.3

40 thru 44 years old

8.9**

11.1

45 years and older

14.8**

15.5

Characteristic

Rate by race:

Rate by Plurality:

Rate by maternal age:
< 15 years old

*

1

most recent data available through the NCHS
**
interpret rate with caution due to low sample size

17

References
1. MacDorman, MF & Kirmeyer, S. The Challenge of Fetal Mortality, NCHS Data Brief,
2009;16:1-8.
2. U.S. Department of Health and Human Services. Healthy People 2010. Retrieved June
12, 2008, from http://www.healthypeople.gov/document/html/objectives/16-01.htm
3. Sliver RM, Varner MW, Reddy U, Goldenberg R, Pinar H, Conway D, Bulkowski R, et
al. Work-up of stillbirth: a review of the evidence. American Journal of Obstetrics &
Gynecology, 2007;196:433-444.
4. Goldenberg, RL, Kirby, R, Culhane, JF. Stillbirth: a review. The Journal of MaternalFetal and Neonatal Medicine, 2004;16:79-94.
5. Ananth CV, Shiliang L, Kinzler WL, & Kramer MS. Stillbirths in the United States, 19812000: An Age, Period, and Cohort Analysis. American Journal of Public
Health;2005:95:2213-2217.
6. Kotelchuck, M. An Evaluation of the Kessner Adequacy of Prenatal Care Index and a
Proposed Adequacy of Prenatal Care Utilization Index. American Journal of Public Health;
1994:84:1414-1420.
7. The Centers for Disease Control and Prevention. Birth Defects: MADCP. Retrieved July
17, 2008, from the CDC Birth Defects website:http://www.cdc.gov/ncbddd/bd/stillbirths.htm
8. Wingate, MS, Alexander, GR, Buekens, P, & Vahratian, A. Comparison of Gestational
Age Classifications: Date of Last Menstrual Period vs. Clinical Estimate. Ann
Epidemiology;2007:17:425-430.
9. Alexander G, et.al. A United States National Reference for Fetal Growth. Journal of
Obstetrics and Gynecology,1996:87:163-168.
10. ACOG Committee on Practice Bulletins. Management of Stillbirth. American Journal of
Obstetrics and Gynecology, 2009;102:748-761.
11. Bender BA. 2007 Health Status and Health Risk Behaviors of Arizonans. Retrieved
November 3, 2009, from: http://www.azdhs.gov/plan/brfs/reports/rpt07.pdf.
12. Gardosi J, Kady SM, McGeown P, Francis A & Tonks A. Classification of stillbirth by
relevant condition at death (ReCoDe): population based cohort study. British Medical
Journal;2005:331:1113-1117.
13. Vergani P, Cozzolino S, Possi E, Cuttin MS, Greco M, Ornaghi S & Lucchini V.
Identifying the causes of stillbirth: a comparison of four classification systems. American
Journal of Obstetrics and Gynecology;2008:199:319.e1-319.e4.

18

To obtain further information, contact:
Jamie Smith, Child Fatality Review Manager
Arizona Department of Health Services
Public Health Prevention Services
Bureau of Women’s and Children’s Health
Assessment and Evaluation Section
150 North 18th Avenue, Suite 320
Phoenix, AZ 85007
Phone: (602) 542-1875
FAX: (602) 364-1496
E-Mail: smithja@azdhs.gov

19