INCIDENCE AND REPORTED CAUSES OF
STILLBIRTHS IN ARIZONA
Fourth Annual Report
September 2008

Prepared by:
Douglas Ritenour
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
Janet Napolitano, Governor
State of Arizona
January Contreras, Acting 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 2003-2007………………………………………………………....

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....................................................................................

13
13
14

Recommendations for Further Study....................................................................

14

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

16

ii

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

Page
15

iii

Figures

Page

1. Stillbirth Rates........................................................................................................

3

2. Stillbirth Rates by Year and Race/Ethnicity..........................................................

4

3. Stillbirth Rates by Maternal Age...........................................................................

5

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

5

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

6

6. Women Entering Prenatal Care by Trimester (excluding unknowns and
missing cases) ........................................................................................................

6

7. Women Reporting Cigarette or Alcohol Use during Pregnancy by Birth Status.

7

8. Stillbirth by Gestational Age................................................................................

8

9. Reported Weight of Stillbirths...............................................................................

8

10. Stillbirths Autopsy by Urban and Rural Counties..............................................

9

11. Stillbirths Autopsied by Reported Weight..........................................................

10

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

11

13. Causes of Stillbirth.............................................................................................

12

14. Top Three Causes of Stillbirths by Gestational Age..........................................

12

iv

Executive Summary
____________________________________________________________
This report completes the annual requirement set forth by the Arizona State Legislature to
present the incidence and causes of stillbirth. The Unexplained Infant Death Council
recommended that analyses include a five-year cohort of stillbirths from 2003 through
2007. Birth certificate data was utilized to draw conclusions about the risks of stillbirth by
women’s age, race, education, 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 has declined slightly, but
not significantly over the past five years. Unless the trend in the overall stillbirth rate
experiences a significant decline in the 2008-2010 cohort, Arizona is unlikely to meet the
Healthy People 2010 objective of 4.1 stillbirths per 1,000 live births plus stillbirths. Racial
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. Other risk markers such
as lower education, teen pregnancy and pregnancy after 35 years of age, and timing of
prenatal care remained consistent with data in previous reports. As expected Maricopa
and Pima counties accounted for the vast majority of stillbirths (83%) over the five-year
cohort.
Length of gestation and delivery weight were correlated with the incidence and causes of
stillbirth, and also the use of autopsy. The majority of stillbirths (51.0%) occurred prior to
28 weeks of pregnancy and weighed less than 1,500 grams. 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 likely to be
conducted on later term stillbirths with greater delivery weight. Although autopsy is
recognized as the most useful procedure in determining cause of death, autopsy was
conducted on fewer than 14% of stillbirths in this cohort. This report did not examine the
medical, legal or infrastructure barriers to increasing the autopsy rate for stillbirths in
Arizona. Data reliability and completeness were issues that restricted a more in depth
examination of the incidence and causes of stillbirth in Arizona from 2003 through 2007.

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. The third annual report compared the 2006
cohort with the baseline cohort (2003). Based on the recommendation of the Unexplained
Infant Death Council, the 2008 Incidence and Reported Causes of Stillbirths report
presents a five-year cohort analysis of fetal deaths from 2003 through 2007.
Methodology
Arizona electronic fetal death certificate data for deaths occurring between 1st of January,
2003 and 31st of December 2007 are summarized in this report. To conduct the analyses,
an electronic file was created merging data from the five-year cohort. Data obtained were
from files 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 and
the limitations of these data are considered.
Arizona 2003-2007
As per the Arizona Vital Records Fetal Death Certificate database, there were a total of
2,702 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
2003 through the 31st of December 2007. Figure 1 shows that the stillbirth rate ranged
from a high of 6.6 per 1,000 live births and fetal deaths in 2001 to a low of 5.3 in 2006.
Although the stillbirth rate increased from an “historic low” of 5.3 in 2006 to 5.6 in 2007, the
rates were not significantly different.* The stillbirth rate in Arizona for the combined fiveyear 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 2004.1 Nevertheless, the stillbirth rate in Arizona for 2007 remains
above the Healthy People 2010 objective of 4.1 per 1,000 live births and fetal deaths.2 If

*

P =.22 (CI: -0.10 - 0.82)

2

Arizona had met the Healthy People 2010 standard from 2003 to 2007, approximately 700
stillbirths would have been averted.
Figure 1. Stillbirth Rates (per 1,000 live births + fetal deaths)
Arizona 2000-2007

8
7
6
Rate

5

6.2

6.6

6.3

5.9

5.4

5.5

5.3

2004

2005

2006

5.6

4
3
2
1
0
2000

2001

2002

2003

2007

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 in the 2003-2007 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; the spontaneous
termination of pregnancy at 20 or more weeks gestation. In addition, it is likely that many of
these women also delivered a live infant and are part of the 2003-2007 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 ten 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 per 1,000 live births
and fetal deaths. The rate of stillbirth among singleton pregnancies (5.3 per 1,000 liver
births and fetal deaths) was significantly less than for multiple pregnancies.* 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.
*

P<0.0001(CI: 8.5 - 8.9)

3

Finally, uncertainty exists 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 2007 time period in Arizona. The stillbirth rate ranged from a low of 4.3 for Asian
and Pacific Islander women to a high of 9.9 per 1,000 live births and fetal deaths for
African American women. Stillbirth rates by race/ethnicity for the 2003-2007 cohort showed
a decline across all racial and ethnic categories compared to the 2000-2004 cohort.
However, a significant disparity in stillbirth rates remains between African American
women and other racial/ethnic groups.* Pregnant African American women had 1.85 times
the risk of having a stillbirth as non-African American women. This disparity is persistent in
stillbirth rates across the United States.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 Year and
Race/Ethnicity, Arizona 2003-2007 (n=2,690)

Asian/Pacific Islander (n=62)

4.3

White (n=1042)

5.1

Hispanic (n=1225)

5.7

American Indian (n=185)

6.0

African American (n=176)

9.9
0

2

4

6

8

10

12

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. Women under 20 years of
age had a significantly 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 twice as great as women in their twenties.***

*

P<0.0001 (CI: 3.0 - 5.9)
P<0.0001 (CI: 1.5 - 1.96)
***
P<0.0001 (CI: 2.13 - 3.66)
**

4

Figure 3. Stillbirth Rates (per 1,000 live births + fetal deaths) by Maternal Age
Arizona 2003-2007
(n=2,690)

Rate

20

13.9
7.4

7.2

10

6.2

5

4.8

10

5.1

0

Less
than 15
years
(n=13)

15 to 17 18 to 19 20 to 24 25 to 29 30 to 34 35 to 39 40 years
years
years
years
years
years
years and older
(n=154) (n=244) (n=673) (n=654) (n=507) (n=341) (n=104)

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 (6.7 per 1,000 births and fetal deaths)
experienced significantly higher rates of stillbirths than women with 13 years or more of
education (4.8 per 1,000).*
Figure 4. Stillbirth Rates (per 1,000 live births + fetal deaths) by Level of Education
Arizona 2003-2007
(n=2,648)

10
Rate

6.3
4.5

5
0
12 Years and less (n=1774)

13 Years and more (n=874)

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,
*

P<0.0001(CI: 1.5 - 2.1)

5

she may require more prenatal care visits than a woman without an identified risk factor,
thus reducing her risk for a stillbirth. 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 addressed. Because of the difficulty in interpreting
adequacy of prenatal care measures for fetal deaths, the analysis will not be 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 from 2003 through 2007. Women
experiencing stillbirths entered prenatal care in the first trimester less frequently than
women giving birth to live infants. However, 10 percent of the stillbirth cases were missing
data for trimester of entry into prenatal care.
Figure 5. Women Entering Prenatal Care by Trimester
Arizona 2003-2007
100%
Stillbirths (n=2,702)

71% 77%

Live Births (n=484,706)

50%
14% 16%

10%

2% 4%

4% 3%

3rd Trimester

No Prenatal
Care

<1%

0%
1st Trimester

2nd Trimester

Prenatal Care
Missing

In a similar analysis, the cases where month of entry into prenatal care was unknown or
missing were removed. Figure 6 shows when these cases were excluded, timing of entry
into prenatal care was very similar for mothers of stillborns and mothers delivering live
infants. Although timing of entry into prenatal care is similar between the two groups, the
limitations of the data prevent further exploration of hypothesized relationships between
prenatal care and stillbirth.

Figure 6. Women Entering Prenatal Care by Trimester
Arizona 2003-2007
(excluding unknowns and missing cases)
100%
Stillbirths (n=2,436)

78% 77%

Live Births (n=482,780)

50%
15% 16%
2%

4%

4%

3%

0%
1st Trimester

2nd Trimester

3rd Trimester

No Prenatal Care

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. 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

Although cigarette and alcohol use during pregnancy are recorded on the fetal death
certificate, they were not analyzed in the three previous annual reports. The proprietor of
the fetal death certificate data noted improved data quality obtained from hospitals over
these two risk behaviors from 2006 onward. Therefore, this analysis is restricted to women
with known responses to the questions of smoking or drinking in the 2006 through 2007
stillbirth cohort (n= 1,061 smoking responses; n= 1,056 drinking responses) and live birth
cohort (n= 204,046 smoking responses; n= 203,634 drinking responses). The amount of
cigarettes smoked each day and number of alcoholic drinks consumed each week is also
collected on the fetal death certificate; however, more than 85 percent of cases lack data
across these two fields. The Arizona fetal death certificate does not contain information
about cigarette or alcohol use by trimester. Figure 7 shows the percentage of women who
reported smoking cigarettes or drinking alcohol during pregnancy for 2006 through 2007.
Figure 7. Women Reporting Cigarette or Alcohol Use during Pregnancy by
Birth Status
Arizona 2006-2007

100%
Smoking

Alcohol

50%
9%
2%

0%

Delivered Stillbirth

5%

<1%

Delivered Live Birth

Nine percent of women who had a stillbirth reported smoking and 2 percent reported
drinking while pregnant. Only 5 percent of women delivering a live birth reported smoking
and less than 1 percent reported drinking alcohol during pregnancy. Within this sample,
the rate of stillbirth among women who reported smoking during pregnancy (9.3 per 1,000
live births + stillbirths) was significantly greater than the rate of stillbirth among nonsmokers (5.0 per 1,000).* The rate of stillbirth for women who reported drinking alcohol
during pregnancy is not presented because of the limited number of responses across this
variable. 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 this data.
*

P<0.0001(CI: 3.98 - 4.62)

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 8 shows the clinical
breakdown of stillbirth by reported early, late, term, and post-term gestational ages.7
Similar to national statistics,3 51 percent of stillbirths in Arizona occurred prior to 28 weeks
gestation and 18 percent were “at term”. It should be noted that gestational age is a
physician’s estimate (clinical estimate) and, therefore may have reliability and validity
issues.8
Figure 8 Stillbirths by Gestational Age
Arizona 2003-2007
(n= 2,696)
100%

51%
50%

29%
18%
1%

0%
less than 28 weeks
(n=1,378)

28 through 36 weeks
(n=785)

37 through 40 weeks
(n=497)

41 weeks or more
(n=36)

Figure 9 shows the reported weight of stillbirths from 2003-2007.

Figure 9. Reported Weight of Stillbirths
Arizona 2003-2007
(n=2,700)

2500-3999 grams
17%
(n=468)

1500-2499 grams
16%
(n=422)

4000+ grams
3%
(n=78)

Less than 350 grams
20%
(n=534)

350-1499 grams
44%
(n=1,198)

8

It is evident from Figure 9 that 44 percent of these stillbirths were reported to weigh
between 350 to 1,499 grams, and 16 percent weighed between 1,500 and 2,499 grams.
Another 20 percent were reported to weigh less than 350 grams and two cases were
missing data for birth weight. Most fetuses that survive to 20 weeks gestation weigh over
350 grams.9 Therefore, while some of these fetuses may have indeed weighed less than
350 grams, it is likely that some of the reported weights of less than 350 grams were data
errors.
County of Occurrence and Frequency of Autopsy
Fetal autopsies are the most useful diagnostic procedure for information on the cause of
death.3 However, only 13.8 percent of all reported stillbirths from 2003-2007 (n=372)
received an autopsy (see Appendix A). The proportion of stillbirths receiving an autopsy
also declined each year from 2004 (16.2 percent) to 2007 (11.1 percent). Additionally, the
quality of data declined each year over the reported autopsy field. Only 0.9 percent of
cases were coded as “unknown” in 2003, but 6.7 percent coded as “unknown” in 2007.

One of the recommendations made by the Unexplained Infant Death Council for the fourth
annual report was to review the proportion of stillbirths that were autopsied in urban versus
rural areas. From 2003 through 2007, the majority of stillbirths occurred in urban counties
(85 percent). Sixty-eight percent of those stillbirths were reported to have occurred in
Maricopa County (n=1,840), 15 percent occurred in Pima county (n=407), and the
remainder occurred in twelve other counties (n=455). 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 more stillbirths were delivered in Maricopa
County than in Pima County, the proportion of stillbirths autopsied was significantly lower
in Maricopa County compared to Pima County.*
Figure 10. Stillbirths Autopsied by Urban and Rural Counties
Arizona 2003-2007
(n=2,702)
100%
Autopsied

84%

Not Autopsied

Unknown

68%

50%

14%

14%

18%

2%

0%
Urban County (n=2,298)

*

Rural County (n=404)

Chi-square 70.39 (2), P<0.0001

9

The proportion of autopsies was also analyzed by race, ethnicity, gestational age, and
reported weight of the fetus. In terms of ethnicity and race, the percentage of stillbirths
delivered by non-Hispanic women that received an autopsy was 14.8 percent compared to
12.5 percent of stillbirths delivered by Hispanic women. The proportions of stillbirths
autopsied for White (15.5 percent), Asian (14.5 percent), and African American (16.0
percent) women were all higher than for stillbirths autopsied for American Indian women
(8.2 percent). However, the high percentage of ‘unknown autopsy status’ among American
Indian stillbirths (12.4 percent) limits the interpretation of the disparity.
Figure 11 shows the percentage of stillbirths that were autopsied by reported gestational
weight. In general, as the reported gestational weight increased, the percentage of
stillbirths autopsied also increased. Just 8.6 percent of stillbirths weighing 1 to 349 grams
were autopsied compared to 21.8 percent of stillbirths weighing 4,000 grams or more.
Significantly more stillbirths occurring at or after 25 weeks gestation were autopsied (16.7
percent) than stillbirths occurring prior to 25 weeks (9.5 percent).*
Figure 11. Stillbirths Autopsied by Reported Weight
Arizona 2003-2007
(n= 2,587)

100%

50%

13%

17%

350 to 1499 grams
(n=1,154)

1500 to 2499
grams (n=397)

9%

20%

22%

2500 to 3999
grams (n=450)

4000+ grams
(n=76)

0%
0 to 349 grams
(n=510)

Figure 12 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 the procedure was only
used slightly more than one-third of the time to ascertain the cause of death in Arizona. It
should be noted that the large proportion of autopsied cases recorded as “unknown”
makes further analysis of this variable unreliable.

*

Chi-square 28.96 (2) P<0.0001

10

Figure 12. Autopsies Used in Determining Cause of Death among
Stillbirths Receiving an Autopsy
Arizona 2003-2007
(n=372)
100%

50%

36%

37%

Autopsy Used (n=132)

Autopsy Not Used (n=138)

27%

0%
Unknown (n=102)

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, the cause of stillbirth often remains unknown, even when a concerted
effort is made to determine the cause of death. Currently, 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.

Currently this coding 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. From 2003 to 2007, there were over 180 distinct
ICD-10 codes used to classify cause of death in the fetal death certificate data. In order to
group these causes into classifications for this report, 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 2003 through 2007 reporting period. As is true
in many studies on the causes of stillbirths3, the cause of death was unknown in the
majority of stillbirths for this time period. In many cases, the lack of a definitive cause of
death may be the result of data reporting issues. Five percent of the stillbirths reviewed for
this report did not have an ICD-10 code listed in the fetal death file, 11 percent of the
stillbirths had invalid ICD-10 codes, 15 percent of the stillbirths had inappropriate ICD-10
codes, 16 percent of the stillbirths were reclassified as “unknown cause” because the ICD10 code listed in the death certificate file did not appear to be a valid ICD-10 code for a
fetal death. Another 20 percent of the stillbirths were coded with an ICD-10 code of P95, or
“fetal death of unspecified cause”. The remaining 33 percent of fetal deaths had ICD-10
codes indicating valid and specific causes of fetal deaths.
*

ICD-10 codes were reclassified according to a matrix created by Dr. Mike Clement of the Arizona Perinatal
Trust in 2006.

11

Figure 13. Causes of Stillbirth
Arizona 2003-2007
(n=2,702)
No ICD-10 Code
5%
(n=135)

Valid and Specific
Cause
33%
(n=892)

Invalid ICD-10
11%
(n=297)
Inappropriate ICD-10
15%
(n=405)

Recoded as Unknown
16%
(n=433)

Fetal Death of
Unspecified Cause
20%
(n=540)

Of the 33 percent of stillbirths with a known cause of death, the most common cause was
cord problems (30 percent), followed by malformations (22 percent), placenta disorders
(20 percent), hypoxia (5 percent) and cardiovascular disease (5 percent). Infection or
inflammation (4 percent), and hydrops fetalis or isoimmunization and hypertension (3
percent each) accounted for the remaining cases where cause of death was known. “Other
causes” were listed for 7 percent of stillbirths.
Figure 14 illustrates 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 14. Top Three Causes of Stillbirth by Gestational Age
Arizona 2003-2007
(n=561)
100%

Malformations
Cord Problems
Placental Disorders

52%
50%
29%
21%

19%

14%

19%

0%
Less than 28 Weeks Gestation (n=361)

37 Weeks Gestation and more (n=200)

12

Within these two gestational age categories, 29 percent of deaths had a reported known
cause of death. The most common causes of death were cord problems, malformations
and placental disorders for both age categories. For stillbirths delivered at less than 28
weeks gestation, malformations (29 percent) accounted for the greatest proportion of
deaths, while cord problems (52 percent) was the most common cause of death for
stillbirths at 37 weeks or more gestation.

DATA QUALITY
When the Incidence and Reported Causes of Stillbirths 2003 Report was presented to the
Unexplained Infant Death Council in April of 2005, there were many concerns regarding
the quality of the data. The Council recommended that the second annual stillbirth report
include an analysis of the quality of the data including a review of problematic fields by
facility or hospital. In response to the concerns regarding data quality and the Council’s
recommendations, a number of data elements are examined annually for data quality. The
analysis for the 2008 Report 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
was 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 should 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 2,702 cases reported in these
files, six did not have data in the reported gestational age field. All six of these cases had a
weight of at least 350 grams indicating that they were an appropriate gestational age for
inclusion in this report. The remaining 2,696 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 The calculation of gestational age by reported last
menstrual period is complicated by missing and unreliable data over 17 percent of cases.
Nevertheless, when using last menses to measure gestational age, approximately 3
percent (n=88) of stillbirths were less than 20 weeks old and half of these cases (n=44)
also had reported 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. Three percent of the cases (n=69) were reported to weigh zero grams and
13

another 17 percent (n=465) were reported to weigh less than 350 grams. No association
was found between zero gram stillbirths and particular delivery facilities.
Quality of Data Fields
The quality of data was examined across all selected variables used in this report. When
more than 5 percent of data was missing, this was cited in the report. Additional variables
that would be useful in the analysis of stillbirth include the amount of cigarettes smoked
per week and the number of alcoholic drinks consumed per day by trimester, and the BMI
of the mother. Although total smoking and alcohol consumption are recorded on the fetal
death certificate, more than 85 percent of cases had no data on the amount consumed.
Also, exposure to second hand smoke is not collected by the fetal death certificate. Weight
gained during pregnancy is also collected on the fetal death certificate. Obesity is
associated with stillbirth.3,4 However, weight gain data was missing over 25 percent of
cases, and neither baseline weight/height (commonly measured at first prenatal visit) nor
BMI are collected on the fetal death certificates. Proposed revisions to the fetal death
certificate (see http://www.azdhs.gov/plan/cert/pdf/fetal.pdf ) include data fields for BMI,
pre-pregnancy weight, and trimester of cigarette use. These revisions along with more
reliable data collection at delivery facilities would bolster future analyses of the risks for
stillbirth.

RECOMMENDATIONS FOR FURTHER STUDY
The Incidence and Reported Causes of Stillbirth Report for 2009 will utilize a one year
cohort of stillbirths (2008) to analyze rates and proportions over the same variables. In
addition, the 2009 Report should consider the following quality improvements;
•

request the assistance of a qualified MD from the Arizona Perinatal Trust to
complete the classification of the causes of stillbirth using Gardosi’s ReCoDe
classification system.10

•

include an appendix of missing data fields that will be sent to the proprietors of the
fetal death certificates as notification of the strengths and weaknesses of data
collection.

•

utilize a format that compares Arizona rates and proportions side-by-side with
national rates and proportions.

•

examine reports on stillbirth from other states in the attempt to include new
analyses.

14

Appendix A
AUTOPSY

County of Delivery
APACHE
COCHISE
COCONINO
GILA
GRAHAM
GREENLEE
MARICOPA
MOHAVE
NAVAJO
PIMA
PINAL
SANTA CRUZ
YAVAPAI
YUMA
Total

Autopsied
0
.0%
14
36.8%
2
4.0%
1
7.7%
0
.0%
0
.0%
220
12.0%
7
10.9%
4
8.0%
87
21.4%
6
18.2%
1
14.3%
13
28.9%
17
15.9%
372
13.8%

Not Autopsied
20
66.7%
19
50.0%
40
80.0%
11
84.6%
14
82.4%
0
.0%
1597
86.8%
45
70.3%
30
60.0%
294
72.2%
24
72.7%
5
71.4%
31
68.9%
87
81.3%
2217
82.1%

Unknown
10
33.3%
5
13.2%
8
16.0%
1
7.7%
3
17.6%
1
100.0%
23
1.3%
12
18.8%
16
32.0%
26
6.4%
3
9.1%
1
14.3%
1
2.2%
3
2.8%
113
4.2%

15

References

1. MacDorman, MF, Munson, ML, & Kirmeyer, S. Fetal and Perinatal Mortality, United
States, 2004;56:1-20.
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. 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.

16

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

17