INCIDENCE AND REPORTED CAUSES OF
STILLBIRTHS IN ARIZONA
Seventh Annual Report
November, 2011

Prepared by:
Dyanne G. Herrera, MPH
Maternal and Child Health Epidemiologist
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

Health and Wellness for all Arizonans
Janice K. Brewer, Governor
State of Arizona
Will Humble, Director
Arizona Department of Health Services

MISSION
To improve the health and wellness of people and communities in Arizona.

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 2010……………………………………………………….............

2
2
2
2

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

3
3
4
5
5
6
7

Characteristics of Stillbirths……………………………………………………..
Occurrence by County …………………………………………………….
Urban and Rural Region …………………………………………….......…
Border and Non-Border Region………………………………………….....
Frequency of Autopsy ………………………………………………...........
Reported Cause of Death……………………………………………….......

8
10
10
11
12
15

Data Quality……………………………………………………………………….
Case Inclusion................................................................................................
Quality of Available Data..............................................................................

17
17
17

Appendices................................................................................................................

19

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

22

ii

Tables

Page

1. Number and Rates of Stillbirths by Region, Arizona, 2010.........................

11

2. Stillbirth Number and Rates by County, Arizona, 2004-2010......................

19

3. Stillbirths: Arizona and the U.S......................................................................

21

Maps
1. Stillbirths in Arizona, 2010

Page
.........................................................................

2. Stillbirth Rates by County, Arizona, 2010 .........................................................

10
20

iii

Figures

Page

1. Stillbirth Rates, 2003-2010.....................................................................................

3

2. Stillbirth Rates by Year and Race/Ethnicity, 2003-2010........................................

4

3. Stillbirth Rates by Maternal Age, 2010..................................................................

5

4. Stillbirth Rates by Level of Education, 2010.........................................................

6

5. Women Entering Prenatal Care by Trimester 2010...............................................

7

6. Women Reporting Cigarette or Alcohol Use during Pregnancy, 2010..................

8

7. Stillbirth by Gestational Age, 2010........................................................................

9

8. Stillbirths by Delivery Weight, 2010 .....................................................................

9

9. Stillbirths Autopsied by Urban and Rural Counties, 2010........................................

12

10. Stillbirths Autopsied by Border and Non-Border Counties, 2010............................

13

11. Stillbirths Autopsied by Reported Weight, 2010.................................................

14

12. Autopsies Used in Determining Cause of Death among Stillbirths Receiving
an Autopsy, 2010..................................................................................................

14

13. Stillbirths with Valid Cause of Death, 2010 ........................................................

15

14. Specific Causes of Stillbirth, 2010........................................................................

16

15. Top Three Causes of Stillbirth by Gestational Age, 2010.....................................

16

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 in Arizona declined slightly
from last year (19%), but did not meet the 2010 Healthy People Objective of 4.1 stillbirths per
1,000. The 2010 rate of stillbirth in Arizona (5.1 per 1,000 live births and fetal deaths) is still
lower than the last reported U.S. rate in 2005 (6.2 per 1,000 live births and fetal deaths).1
The findings in this report show 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 no
prenatal care are also associated with stillbirth in Arizona. Maricopa and Pima Counties
accounted for the vast majority of stillbirths (80 percent) in 2010. The rate of stillbirth among
residents of urban counties (5.2 per 1,000 live births plus stillbirths) was higher than the rate
in rural counties (4.0 per 1,000 live births plus stillbirths). In addition, border counties had a
slight higher stillbirth rate than non-border counties, 5.2 and 5.0 per 1,000 live births plus
stillbirths, respectively (see Appendix A)
Gestational age and birth weight are associated with the incidence and causes of stillbirth.
Stillbirths were more likely to occur at early term (51 percent) rather than at term (19 percent),
and the majority weighed less than 1,500 grams (61 percent). Malformation was reported as
the leading cause of death for early term stillbirths, while cord problems was the leading
cause of death in term/late term stillbirths. Although autopsy is recognized as the most useful
procedure in determining the cause of death, only twelve percent of stillbirths underwent the
procedure. This report did not examine the medical, legal or infrastructure barriers to
increasing the autopsy rate for stillbirths. Arizona utilizes 1989 the U.S. Standard Fetal Death
Certificate that restricts a more in-depth 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. The second annual report examined cases from 2000 through 2004 and the
fifth and sixth annual reports used a one-year cohort of fetal deaths. This year‟s report
examines a one-year cohort of stillbirth infants delivered in 2010.
Methodology
Arizona electronic fetal death certificate data for deaths occurring between the 1st of January,
2010 and the 31st of December 2010 are summarized in this report. To conduct the analyses,
a database was created with fetal death and live birth data from Oracle tables available
through the Bureau of Public Health Statistics within the Arizona Department of Health
Services. These tables 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 𝑅𝑎𝑡𝑒 =

# 𝑜𝑓 𝑓𝑒𝑡𝑎𝑙 𝑑𝑒𝑎𝑡ℎ𝑠
𝑥 1000
# 𝑙𝑖𝑣𝑒 𝑏𝑖𝑟𝑡ℎ𝑠 + # 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 birthweight, age, and geographic region of
stillbirths. Geographic comparisons between rural /urban and border/non-border are
examined. Finally, the reported causes of stillbirth are addressed, limitations of these data
are considered, and input from national and international experts is presented.
Arizona 2010
As per the Arizona Vital Records Fetal Death Certificate database, there were a total of 443
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 period between January
2010 through the 31st of December 2010. Figure 1 shows that in the eight year period from
2003-2010, the stillbirth rate ranged from a high of 5.9 per 1,000 live births and fetal deaths in
2003 to a low of 5.1 per 1,000 live births and fetal deaths seen in 2010. The 2010 rate is

2

significantly different from the baseline rate in 2003.* The stillbirth rate in Arizona for the
combined eight-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 2010 remains 24 percent greater than the Healthy People 2010 objective of 4.1
per 1,000 live births and fetal deaths.2 If Arizona had met the Healthy People 2010 standard
from 2003 to 2010, approximately 1052 stillbirths would have been averted.

Figure 1. Stillbirth Rates (per 1,000 live births + fetal deaths)
Arizona, 2003-2010 (n=4,200)
7

5.9

Rate per 1,000

6

5.4

5.5

5.3

2004
(n=505)

2005
(n=532)

2006
(n=543)

5.6

5.5

5.5

2007
(n=583)

2008
(n=544)

2009
(n=511)

5.1

5
4
3
2
1
0
2003
(n=539)

Arizona

2010
(n=443)

HP 2010

Source: Arizona Birth and Fetal Death Certificates, 2003-2010

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 a 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 Thirtytwo percent of women with data on previous pregnancy in the 2010 stillbirth cohort reported
between one and seven 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 stillborn in 2010 also delivered a live infant and are part of the 2010
live birth cohort. Therefore, determining risk for stillbirth based on previous history of stillbirth
is not possible in this report.
*

p =0.02, (CI: 0.11 - 1.45)

3

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 In Arizona, the rate
of multiple gestation stillbirth was 8.7 per 1,000 live multiple births and fetal deaths. The rate
of stillbirth among multiple gestations was significantly greater than for singleton gestations
(4.9 per 1,000 live singleton births and fetal deaths).*
Although assisted reproductive technology (ART) has been associated with both multiple
gestation and stillbirth, the Arizona fetal and birth certificates do not include data about
pregnancy though ART. There is no consensus about whether multiple fetuses are at
additional risk because they were conceived with ART.3
Race/Ethnicity
Figure 2 shows rates of stillbirths by self-reported race and ethnicity for the 2003 through
2010 time period in Arizona. The stillbirth rate was lowest for White non-Hispanics women
(4.0 per 1,000 live births and fetal deaths) and highest for Black or African American women
(8.9 per 1,000 live births and fetal deaths) in 2010. A significant disparity in stillbirth rates
persisted between Black or African American women and other racial/ethnic groups in 2010.**
Pregnant Black or African American women had more than twice the risk of having a stillbirth
as non-African American women. This disparity is also reflected 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

Figure 2. Stillbirth Rates (per 1,000 live births + fetal deaths) by
Race/Ethnicity, Arizona 2003-2010 (n=4,181)*

Rate per 1,000

15.0

10.0

8.9
5.7
5.1

5.0

4.0

0.0
2003
2004
2005
White non-Hispanic (n=1,593)
Black or African American (n=322)

2006

2007
2008
2009
Hispanic or Latina (n=1,839)

2010

American Indian or Alaska Native (n=317)

Asian or Pacific Islander (n=110)
*Excludes records with unknown race or ethnicity
Source: Arizona Birth and Fetal Death Certificates, 2003-2010

*

p= 0.01,(CI: 0.14 - 7.5)
p<0.0001, (CI:2.9 – 6.5)

**

4

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 older women. The risk of experiencing a stillbirth was
significantly greater for pregnant women 35 years of age and older (8.8 per 1,000 live births
and fetal deaths) compared to women aged 20 to 34 years (4.1 per 1,000 live births and fetal
deaths).*

Figure 3. Stillbirth Rates (per 1,000 live births + fetal deaths)
by Maternal Age, Arizona 2010 (n=442)*
20.0
18.0

18.9

16.0
Rates per 1,000

14.0
12.0
10.0
8.0

10.2

9.4

6.0

8.2
6.1

4.0

5.1

4.7

4.6

18-19
(n=33)

20-24
(n=104)

25-29
(n=114)

2.0

3.8

0.0
<15
(n=1)

15-17
(n=18)

30-34
(n=74)

35-39
(n=75)

40-44
(n=20)

45+
(n=3)

*Excludes records with unknown maternal age
Source: Arizona Birth and Fetal Death Certificates, 2010

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 (5.7 per 1,000 births and fetal deaths) experienced
significantly higher rates of stillbirth than women with 13 years or more of education (4.3 per
1,000 live births and fetal deaths).**

*

p< 0.0001 (CI:2.9 – 6.5)
p=0.03 (CI:0.14 – 2.0)

**

5

Figure 4 . Stillbirth Rates (per 1,000 live births and fetal deaths)
by Years of Education, Arizona 2010 (n=404)*
6.0

Rate per 1,000

5.0

5.7

4.0

4.3

3.0
2.0
1.0
0.0
12 years or less

13 years or more

*Excludes records with unknown education and maternal age less than 19
Source: Arizona Birth and Fetal Death Certificates, 2010

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 trimester of entry into prenatal care for both women delivering stillbirths
and women delivering live births in 2010. Delivery status (stillbirth or live birth) was not
associated with first trimester prenatal care. However, no prenatal care was strongly
associated with poor delivery outcome.*

*

Chi-square=53.9(1), p<0.0001

6

Figure 5. Percent of Women Delivering a Live Birth or Stillbirth
by Timing of Prenatal Care*, Arizona 2010
90.0%

80.2% 82.1%

80.0%
70.0%
60.0%
50.0%
40.0%
30.0%
20.0%

13.5% 13.1%

10.0%

0.2% 3.2%

0.0%
1st Trimester

2nd Trimester
Stillbirths

3rd Trimester

6.0%
1.6%
No Prenatal Care

Live Births

*Excludes misising records
Source: Arizona Birth and Fetal Death Certificates, 2010

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 been 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 2010 stillbirth cohort (n= 422 smoking responses; n= 422 drinking responses) and live
birth cohort (n= 86,873 smoking responses; n= 86,734 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 2010 stillbirth and live birth cohorts.

7

Figure 6 . Percent of Women Reporting Cigarette Use or Drinking
Alcohol During Pregnancy* by Delivery Status, Arizona 2010
7.0%
6.0%

6.4%

5.0%

4.7%

4.0%
3.0%
2.0%

1.2%

0.52%

1.0%
0.0%
Sillbirths

Live Birth
Tobbaco use

Alcohol use

*Excludes records with missing data in tabacco and alcohol use questions
Source: Arizona Birth and Fetal Death Certificates, 2010

Approximately six percent (n=27) of women who had a stillbirth reported smoking and one
percent (n=5) reported drinking while pregnant. Only five percent (n= 4,063) of women
delivering a live birth reported smoking and less than one percent (n=453)reported drinking
alcohol during pregnancy. Within this sample, the rate of stillbirth among women who
reported smoking during pregnancy (6.6 per 1,000 live births and stillbirths) was not
significantly greater than the rate of stillbirth among non-smokers (4.7 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.

CHARACTERISTICS OF STILLBIRTHS
Cases in the fetal death certificates are defined by gestational age, and when age is not
available, birth 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
statistics3, approximately 52 percent of stillbirths in Arizona occurred prior to 28 weeks
gestation and approximately 19 percent were „at term‟ (37-40 weeks gestation). 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 Therefore, it is possible
that some infants were delivered prior to 20 weeks and were misclassified miscarriages.

*

p=0.09 (CI: -0.6 – 4.4)

8

Figure 7. Percent of Stillbirths by Gestational Age, Arizona 2010
(n=441)*
60.0%
50.0%

51.5%

40.0%
30.0%

28.8%
20.0%

18.8%
10.0%

0.91%
0.0%
20 -27 weeks
(n=227)

28 -36 weeks
(n=127)

37 - 40 weeks
(n=83)

41 or more weeks
(n=4)

*Excludes records with missing gestational age
Source: Arizona Birth and Fetal Death Certificates, 2010

Figure 8 shows the reported weight of stillbirths from the 2010 cohort. It is evident from
Figure 8 that approximately 36 percent of stillbirths delivered in 2010 were reported to weigh
between 350 to 1,499 grams, 17.8 percent weighed between 1,500 and 2,499 grams, and
16.7 percent weighed 2,500 to 3,999 grams. Macrosomic stillbirths (4,000 grams or more)
comprised 4.5 percent of the cohort. Another 24.8 percent were reported to weigh less than
350 grams.

Figure 8. Percent of Stillbirths by Delivery Weight, Arizona 2010
(n=441)*
40.0%
35.0%

36.1%

30.0%
25.0%
20.0%

24.8%

15.0%

17.8%

16.7%

10.0%
5.0%

4.5%

0.0%
Less than 350
grams (n=110)

350 - 1,499 grams
(n=160)

1,500 - 2,499
grams (n=79)

2,500 - 3,499
grams (n=74)

4,000 or more
grams (n=20)

*Excludes records with missing weight
Source: Arizona Birth and Fetal Death Certificates, 2010

9

Occurrence by County
In 2010, approximately 65 percent of stillbirths were delivered by residents of Maricopa
County (n=289), 14 percent in Pima county (n=64), and the remainder of stillbirths with
known maternal residence occurred in 11 other counties (n=90). Map 1 shows the distribution
of 2010 stillbirths by county.

Map 1. Stillbirths in Arizona, 2010 (n=443)

Urban and Rural Region
Four counties are considered to be urban in Arizona, Maricopa, Pima, Pinal and Yuma.15 The
rest are rural. In 2010 the stillbirth rate in urban counties was 5.2 per 1,000 live births and
stillbirths and for rural counties 4.0 per 1,000* (see Table 1). Although majority of stillbirths in
2010 continued to occur among female residents of urban counties, rates of stillbirth in each
urban county varied due to the relatively small size of rural populations. For instance,
stillbirths in rural counties ranged from 0.0 to 6.1 per 1,000 live births and stillbirths compared
to urban counties that ranged from 4.6 to 5.3 per 1000 (see Appendix A).

*

Not statistically significant difference (p-value= 0.08)

10

In urban counties, the majority of stillbirths where to Hispanics, 42.2% (n=187) followed by
white women, 33.8% (n=133). In rural counties the majority of stillbirths where to white
women, 46.0% followed by Hispanics (22%) and American Indians (22%). No significant
difference was seen on stillbirth rates and maternal risk factors such as mother‟s education,
age, prenatal care initiation, and smoking of stillbirths occurring between urban and rural
counties. The small number of cases in rural region limits interpretation of maternal risk
factors that may be associated with a stillbirth.
Border and Non-border Region
The U.S. Mexico border region was defined as counties within 100km south and north of the
U.S.-Mexico international border line by the U.S.-Mexico La Paz Agreement in 1983.13 The
border region is culturally, economically and politically influenced by both countries due to the
constant movement of the population across the border. 13 This fluidity creates a diverse and
unique population that endures different health burdens than other regions in both countries.
A greater proportion of inhabitants of the U.S. border region live below the federal poverty
level compared to the rest of the United States, and women are significantly more likely to be
living in poverty than men. United States border residents also have lower levels of
education than the national average and they are also less likely to have health
insurance.13,14 Overall, the border region experiences higher rates of communicable and
chronic diseases, than other areas of Mexico or the US.14 Therefore is important to examine
differences in health outcomes in the border counties.
In Arizona, four counties: Cochise, Pima, Santa Cruz and Yuma are considered part of the
border region. The stillbirth rate in border counties was 5.2 per 1000 live births and stillbirths
and in non-border counties was 5.0 per 1,000* (see Table 1). It is likely that there is under
reporting of stillbirths in the border counties, because of women seeking healthcare in Mexico
for a stillbirth due to the highly fluid population. The majority of stillbirths were among
Hispanics in both border and non-border counties, 53.8% and 42.3% respectively. No
significant difference was seen on stillbirth rates and maternal risk factors such as mother‟s
education, age, prenatal care initiation, and smoking in stillbirths occurring in border and nonborder counties. Underreporting and small number of cases in border counties limits
interpretation of maternal risk factors associated with stillbirths.
Table 1: Number and Rate of Stillbirths by Regions, Arizona, 2010
Number

Rate per 1,000*

Border Counties

93

5.2

Non-Border Counties

350

5.0

Urban Counties

393

5.2

Rural Counties

50

4.0

*Per 1,000 live births and stillbirths.
Note: Urban counties include Maricopa, Pima, Pinal and Yuma. All other counties are considered rural. Border Counties
include Cochise, Pima, Santa Cruz, and Yuma. All other are considered non-border counties.

*

Not statistically significant difference (p-value= 0.74)

11

Frequency of Autopsy
Fetal autopsies are the most useful diagnostic procedure for information on the cause of
death.3,9 However, only twelve percent (n=48) of stillbirths with complete data in 2010
received an autopsy. The proportion of stillbirths receiving an autopsy in 2010 has decreased
from a high of 16.4 percent in 2004. Additionally, the quality of autopsy reporting has declined
over the autopsy field in the fetal death certificates. Less than one percent of cases were
coded as “unknown” in 2003, but six percent (n=27) were coded as “unknown” in 2010.
Figure 9 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. The proportion of
stillbirths autopsied was greater in Pima County compared to Maricopa County (12.7 percent
compared to 10.5 percent), the difference was not significant.

Figure 9. Percent of Stillbirths Receiving Autopsy by Urban and
Rural Areas* Arizona 2010 (n=443)
100.0%
90.0%

87.8%

80.0%
70.0%
60.0%
50.0%
40.0%

46.0%
38.0%

30.0%
20.0%
10.0%
0.0%

16.0%

2.0%

10.2%
Urban (n=393)
Autopsy

Rural (n=50)
No Autopsy

Unknown

*Urban areas include Maricopa, Pima, Pinal, and Yuma Counties. All other counties are considered rural.
Source: Arizona Birth and Fetal Death Certificates, 2010

Figure10 shows the proportion of stillbirths delivered in border and non-border counties that
received an autopsy. The border counties had a slight higher proportion of “unknown”
autopsied cases ( 8.6 percent) than non-border counties (5.4 percent). Also, a slight higher
proportion of stillbirths were autopsied in border counties(12.9 percent) than in non- border
counties (10.3 percent). The difference seen between the border and non-border counties
was not significant.

12

Figure 10. Percent of Stillbirths Receiving Autopsy by Border
and Non-Border Areas* Arizona 2010 (n=443)
90.0%
80.0%

84.3%

78.5%

70.0%
60.0%
50.0%
40.0%
30.0%
20.0%
10.0%
0.0%

8.6%
12.9%

10.3%
Border (n=93)
Autopsy

5.4%

Non-border (n=350)
No Autopsy

Unknown

*Border areas include Cochise, Pima, Santa Cruz, and Yuma Counties. All other counties are considered non-border.
Source: Arizona Birth and Fetal Death Certificates, 2010

The proportion of autopsies for cases with complete data was also analyzed by race,
ethnicity, gestational age, and reported weight of the fetus. In terms of race and ethnicity
among stillbirths cases autopsied 14.1 percent where Hispanics, 5.8 percent White, 12.8
percent African American , 16.7 percent American Indian women, and 5.9 percent Asian or
Pacific Islander. However, the high proportion of stillbirths with „unknown autopsy status‟
limits interpretation of any disparity based on race or ethnicity.
Although half of all stillbirths were delivered prior to 28 weeks gestation in 2010, only 7.0
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 (14
percent) and those occurring very early term.
Figure 11 shows the percentage of stillbirths that were autopsied by reported gestational
weight. In 2010 there was no discernible trend in autopsy by weight of stillbirth.

*

Includes only records with complete data over autopsy field.

13

Figure 11. Percent of Stillbirths Autopsied by Delivery Weight
Arizona 2010
25.0%
20.0%

19.9%
15.0%

13.5%

15.0%

10.0%

10.0%
5.0%

3.6%
0.0%
< 350 grams
(n=4)

350-1499 grams
(n=16)

1500-2499 grams 2500-3499 grams
(n=15)
(n=10)

> 4000 grams
(n=3)

Source: Arizona Birth and Fetal Death Certificates, 2010

Figure 12 shows the percentage of autopsies that were successful in determining 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 only used onethird of the time to ascertain the cause of fetal demise in Arizona.

Figure 12. Percent of Autopsies Used to Determine Cause of
Death among those Stilbirths Receiving Autopsy, Arizona 2010
(n=48)
60.0%
50.0%

50.0%
40.0%
30.0%
20.0%

25.0%

25.0%

10.0%
0.0%
Autopsy used (n=12)

Autopsy not used (n=24)

Unknown (n=12)

Source: Arizona Birth and Fetal Death Certificates, 2010

14

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 2010 there were 44 distinct ICD-10
codes used to classify cause of death in the fetal death certificate data. Using methods
developed by Dr. Mike Clement at Arizona Department of Health Services, the ICD-10 codes
and their associated descriptions were reclassified into categories based on their similarities
and potential prevention efforts.
Figure 13 shows causes of stillbirths for the 2010 reporting period. As is true in many studies
on the causes of stillbirths3, the cause of death was unknown in approximately 51 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 eight percent of the stillbirths had an inappropriate ICD-10 code,
four percent of the stillbirths had an invalid ICD-10 code. The remaining 36 percent of fetal
deaths had ICD-10 codes indicating a valid and specific cause of deaths.

Figure 13. Percent of Stillbirths by Recoded Cause of Death*
Arizona 2010 (n=443)
1.1%
7.9%

4.1%

Unknown (n=227)
Valid and Specific (n=158)

51.2%
35.7%

Inappropriate ICD-10 Codes
(n=35)
Invalid ICD-10 Codes (n=18)
Other (n=5)

*Recoded ICD-10 groups developed by Dr. Mike Clement at ADHS in 2006
Source: Arizona Fetal Death Certificates, 2010

*

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

15

Of the stillbirths with a known and specific cause of death (Figure 14), the most common
causes were cord problems (32.3 percent), malformation (24.7 percent), and placental
disorders (18.2 percent). None of the other recoded causes of death accounted for more than
nine percent of stillbirths with valid ICD-10 data.

Figure 14. Specific and Valid Causes of Stillbirth
Arizona 2010 (n=158)

Placental disorders (n=29)
Maternal hypertension (n=1)

18.2%

0.6%

Malformation (n=39)

24.7%

Inflammation/infection (n=14)
IUGR (n=1)

8.9%
0.6%

Hypertension (n=6)

3.8%

Hydrops fetalis or isoimmunization (n=6)

3.8%

Hematologic disorder (n=2)

1.3%

Cord problems (n=51)

32.3%

Cardiovascular (n=9)
0.0%

5.7%
5.0%

10.0% 15.0% 20.0% 25.0% 30.0% 35.0%

*Intrauterine growth restriction refers to a fetus whose weight is below the 10th percentile for its gestational age.
Source: Arizona Fetal Death Certificates, 2010

Figure 15 shows the top three reported causes of death by gestational age categories.

Figure 15. Top Three Causes of Stillbirth by Length of Gestation
Arizona 2010 (n=119)*
70.0%
60.0%

65.4%

50.0%
40.0%
30.0%
20.0%

45.5%

44.7%

30.9%
23.6%

10.0%

29.0% 26.3%

23.0%
11.5%

0.0%
20 to 27 weeks
Cord problems

28 to 36 weeks
37 or more weeks
Malformation Placental disorders

*Exclude records with missing gestational length
Source: Arizona Fetal Death Certificates, 2010

16

Forty percent of stillbirths delivered at term or late term had a specific cause of death, while
only 35 percent did delivered at less than 28 weeks.* 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 (65.4 percent) accounted for the
greatest proportion of deaths, while malformation (45.5 percent) was the most common
cause of death for very early term stillbirths.

DATA QUALITY
The analysis for the 2010 Incidence and Reported Causes of Stillbirth in Arizona consisted of
a review of frequencies of selected variables to determine the percentage of cases with outof-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 443 cases reported in these files, two
records did not have data in the field for reported gestational age. These records had weights
of at least 350 grams indicating that the stillbirths were likely of an appropriate gestational
age for inclusion in this report. The remaining 441 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 16 percent of cases. When using
date of last menses to measure gestational age for those records with complete and reliable
data, approximately two percent (n=9) of stillbirths were less than 20 weeks old and nearly
two-third of these cases (n=6) 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. Approximately 25 percent (n=110) of stillbirths in the data set were reported to weigh
less than 350 grams and all records contained a delivery weight.
Quality of Available Data
Additional variables collected on a revised fetal death certificate would improve the quality of
this report. These variables 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
*

Chi-square 0.491(1) p=0.48

17

Arizona10 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. However, Arizona will not adopt this certificate until 2012. The 2003 Fetal
Death Certificate will 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.11,12 Improved classification systems that rely on data collected in the 2003 Fetal
Death Certificate will improve the validity of this report.

18

Appendix A
Table 1: Stillbirth Number and Rates by County, Arizona, 2004-2010
Total Number of Stillbirths*

Rate of Stillbirths**

2004
505

2005
532

2006
543

2007
583

2008
544

2009
511

2010
443

2004
5.4

2005
5.5

2006
5.3

2007
5.6

2008
5.5

2009
5.5

2010
5.1

Apache

5

7

4

9

8

2

2

3.7

5.4

3.4

7.7

6.6

1.6

1.8

Cochise

10

14

12

13

7

16

11

5.5

7.9

6.6

7

3.9

8.7

6.1

Coconino

7

9

14

9

7

12

5

3.4

4.3

6.8

4.2

3.5

6.3

2.8

Gila

2

3

11

4

6

8

2

3

4.6

16.5

5.7

8.5

11

3.0

Graham

2

2

2

0

5

2

0

4.4

4.4

3.7

0

7.7

3.1

0.0

Greenlee

1

1

0

0

1

0

0

9.6

10

0

0

7.6

0

0.0

La Paz

4

0

0

0

2

0

1

17

0

0

0

8.1

0

5.0

Maricopa

339

330

351

360

350

312

290

5.6

5.3

5.3

5.4

5.6

5.4

5.3

Mohave

11

19

15

17

9

14

8

5

8.4

6.1

6.9

3.9

6.3

3.9

Navajo

12

15

13

15

15

11

8

6.7

7.8

6.9

7.4

7.7

5.8

4.6

Pima

54

68

79

88

73

68

64

4.1

5.2

5.7

6.3

5.4

5.3

5.2

Pinal

14

21

17

39

33

29

24

4.5

5.7

3.8

7.3

5.7

5.4

4.8

Santa Cruz

4

5

3

0

6

3

3

4.9

6.4

4

0

7.5

3.9

4.3

Yavapai

15

7

10

14

3

16

10

7.4

3.3

4.2

5.7

1.4

7.7

5.5

Yuma

25

30

12

14

18

18

15

7.5

9

3.6

4.3

5.3

5.5

4.6

Unknown

0

0

0

0

1

0

0

NA

NA

NA

NA

NA

NA

NA

ARIZONA

*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 and stillbirths.
Note: Urban counties include Maricopa, Pima, Pinal and Yuma. All other counties are considered rural. Border Counties include Cochise, Pima, Santa Cruz, and Yuma. All other are
considered non-border counties.
Source: Arizona Birth and Fetal Death Certificates, 2004-2010

19

Map 2: Stillbirth Rates by County, Arizona, 2010

20

Appendix B
Table 2: Stillbirths: Arizona and the U.S.
Characteristic

Arizona 2010

U.S. 2005*

Total number

443

25,894

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

5.1

6.2

Rate by race:
Black or African American

8.9

11.1

American Indian or Alaskan Native

5.1

6.2

Asian or Pacific Islander

5.1

4.8

Hispanic or Latina

5.7

5.4

White non-Hispanic

4.0

4.8

Singleton

4.9

5.9

Twin

8.6

16.1

24.3**

27.2

9.4**

12.2

15 thru 17 years old

6.1

7.5

20 thru 24 years old

4.7

5.9

25 thru 29 years old

4.6

5.5

30 thru 34 years old

3.8

5.8

35 thru 39 years old

8.2

7.3

40 thru 44 years old

10.2

11.1

45 years and older

18.9**

15.5

Rate by Plurality:

Triplet or more
Rate by maternal age:
< 15 years old

*

most recent data available through the NCHS 1
**
interpret rate with caution due to low sample size

21

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;196:433444.
4. Goldenberg, RL, Kirby, R, Culhane, JF. Stillbirth: a review. The Journal of Maternal-Fetal and
Neonatal Medicine, 2004;16:79-94.
5. Ananth CV, Shiliang L, Kinzler WL, & Kramer MS. Stillbirths in the United States, 1981-2000: 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;2007:17:425430.
9. ACOG Committee on Practice Bulletins. Management of Stillbirth. American Journal of Obstetrics
and Gynecology, 2009;102:748-761.
10. 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.
11. 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;2005:331:11131117.
12. 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.
13. Commission, U.S.-M.B.H., Healthy Border 2010. 2003, United States-Mexico Border Health
Commission: El Paso, Texas.
14. U.S. Department of Health and Human Services, H.R.a.S.A., Women's Health USA 2009,
H.R.a.S.A. U.S. Department of Health and Human Services, Editor. 2009, U.S. Department of Health
and Human Services: Rockville, Maryland.
15. Centers for Disease Control and Prevention. Metropolitan Statistical Areas and their component
counties for the United States.

22

To obtain further information, contact:
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) 364-1400
FAX: (602) 364-1496
E-Mail: herrerd@azdhs.gov

23