INCIDENCE AND REPORTED CAUSES OF
STILLBIRTHS IN ARIZONA
Sixth Annual Report
October, 2010

Prepared by:
Douglas Ritenour, 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

Leadership for a Healthy Arizona
Janice K. Brewer, Governor
State of Arizona
Will Humble, 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 2009……………………………………………………….............

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
10
12

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

15
15
16

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

17

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

19

ii

Tables

Page

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

17

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

18

iii

Figures

Page

1. Stillbirth Rates, 2003-2009.....................................................................................

3

2. Stillbirth Rates by Year and Race/Ethnicity, 2003-2009........................................

4

3. Stillbirth Rates by Maternal Age, 2009..................................................................

5

4. Stillbirth Rates by Level of Education, 2009.........................................................

5

5. Women Entering Prenatal Care by Trimester 2009...............................................

6

6. Women Reporting Cigarette or Alcohol Use during Pregnancy, 2009..................

7

7. Stillbirth by Gestational Age, 2009........................................................................

8

8. Reported Weight of Stillbirths, 2009 .....................................................................

9

9. Stillbirths Autopsied by Urban and Rural Counties, 2009........................................

10

10. Stillbirths Autopsied by Reported Weight, 2009.................................................

11

11. Autopsies Used in Determining Cause of Death among Stillbirths Receiving
an Autopsy, 2009..................................................................................................

12

12. Stillbirths with Valid Cause of Death, 2009 ........................................................

13

13. Specific Causes of Stillbirth, 2009........................................................................

14

14. Top Three Causes of Stillbirth by Gestational Age, 2009.....................................

14

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 remained
unchanged over the past five years. The 2009 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 Although
the total number of stillbirths in Arizona fell six percent from 2008 (n=544) to 2009 (n=511),
the rate of stillbirth in Arizona did not experience a similar decline due to a reduction in live
births in 2009.
This report also shows that disparities in the rate of stillbirths persist. Among different
racial and ethnic groups, African American women were 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 remained
significantly associated with stillbirth in Arizona. Maricopa and Pima Counties accounted
for the vast majority of stillbirths (74 percent) in 2009. In 2009 the rate of stillbirth among
residents of urban counties (5.4 per 1,000 live births plus stillbirths) was lower than the
rate in rural counties (6.1 per 1,000 live births plus stillbirths) (see Appendix A).
Gestational age and delivery weight were associated with the incidence and causes of
stillbirth. Stillbirths were more likely to occur at early term (52 percent) rather than at term
(14 percent), and the majority weighed less than 1,500 grams (64 percent). Malformation
was 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 is recognized as the
most useful procedure in determining the cause of death; however, only nine percent of
stillbirths underwent the procedure in Arizona. This report did not examine the medical,
legal or infrastructure barriers to increasing the autopsy rate for stillbirths. Data utilized for
this report were obtained from the 1989 U.S. Standard Fetal Death Certificate which limits
analysis of the characteristics of women delivering a stillbirth and additional causal factors
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 fourth annual report also used a five-year cohort of fetal deaths from 2003 through
2007. This year‟s report examines a one-year cohort of stillbirth infants delivered in 2009.
Methodology
Arizona electronic fetal death certificate data for deaths occurring between the 1st of
January, 2009 and the 31st of December 2009 are summarized in this report. To conduct
the analyses, a dataset 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 data were for stillbirths
reported to have occurred at or after 20 weeks of gestation, and if gestational age was
unknown, the deaths of fetuses of at least 350 grams. Data analysis was restricted to
delivering women with Arizona residence only.
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 2009
As per the Arizona Vital Records Fetal Death Certificate database, there were a total of
511 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
2009 through the 31st of December 2009. 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
2009 rate is not significantly different from the baseline rate in 2003.* The stillbirth rate in
Arizona for the combined seven-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 2009 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
met the Healthy People 2010 standard from 2003 to 2009, approximately 979 stillbirths
would have been averted.
*

p =0.25 (CI: -0.30 - 1.10)

2

7.0

Figure 1. Stillbirth Rates (per 1,000 live births + fetal deaths)
Arizona 2003-2009 (n=3,757)
5.9

Rate per 1,000

6.0

5.5

5.4

5.3

5.6

5.5

5.5

5.0
4.0
3.0

2.0
1.0
0.0
2003
(n=539)

2004
(n=505)

2005
(n=532)
Arizona

2006
(n=543)

2007
2008
(n=583) (n=544)
HP 2010

2009
(n=511)

Source: Arizona Birth and Fetal Death Certificates, 2003-2009

MATERNAL RISK MARKERS
Few hypothesized risks have been causally linked to stillbirth.3 Maternal risk markers
include physical, behavioral and environmental risks that 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
Thirty-one percent of women with valid data in the 2009 stillbirth cohort reported between
one and eight 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 2009 also delivered a live infant and are part of
the 2009 live birth cohort. Therefore, determining the 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 In
Arizona, the rate of multiple gestation stillbirth was 12.4 per 1,000 live multiple births and
fetal deaths. The rate of stillbirth among multiple gestations was significantly greater than
for singleton gestations (5.3 per 1,000 live singleton births and fetal deaths).*
*

p<0.0001(CI: 5.9 - 8.3)

3

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 with ART. 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 reported race/ethnicity of the mother for the 2003
through 2009 time period in Arizona. The stillbirth rate was lowest for Asian or Pacific
Islander women (3.2 per 1,000 live births and fetal deaths) and highest for Black or African
American women (11.7 per 1,000 live births and fetal deaths) in 2009. A significant
disparity in stillbirth rates persisted between Black or African American women and other
racial/ethnic groups in 2009.* 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

15.0

Figure 2. Stillbirth Rates (per 1,000 live births + fetal deaths) by
Race/Ethnicity, Arizona 2003-2009 (n=3,741) *

rate per 1,000

13.4

11.7
10.0

5.0

6.9
6.3
4.5
3.2

7.4
5.3
4.9
3.2

0.0
2003

2004

2005

White non-Hispanic (n=1,437)
Black or African American (n=283)
Asian or Pacific Islander (n=93)

2006

2007

2008

2009

Hispanic or Latina (n=1,641)
American Indian or Alaska Native (n=287)

*excludes records with unknown race or ethnicity
Source: Arizona Birth and Fetal Death Certificates, 2003-2009

Maternal Age
Age is a risk marker for stillbirth. Maternal age is used as a proxy measure of unknown
and unmeasured physiological changes that are associated with 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 (8.7 per
1,000 live births and fetal deaths) compared to women aged 20 to 34 years (4.9 per 1,000
live births and fetal deaths).**
*

p<0.0001, (CI:1.3 - 5.2)
p<0.0001, (CI:2.0 – 5.6)

**

4

14.0

Figure 3. Stillbirth Rates (per 1,000 live births + fetal deaths)
by Maternal Age, Arizona 2009 (n=510)*
11.8

rate per 1,000

12.0
10.0

8.0

7.4

8.0

5.4

6.0

4.6

4.7

20 to 24
years
(n=111)

25 to 29
years
(n=126)

5.3

4.0
2.0
0.0

0.0
Less than
15 years
(n=0)

15 to 17
years
(n=26)

18 to 19
years
(n=40)

30 to 34
years
(n=105)

35 to 39
years
(n=76)

40 years
and older
(n=26)

*one record missing mother's age
Source: Arizona Birth and Fetal Death Certificates, 2009

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 (5.8 per 1,000 births and fetal deaths)
experienced significantly higher rates of stillbirth than women with 13 years or more of
education (4.5 per 1,000 live births and fetal deaths).*

7.0

Figure 4. Stillbirth rates (per 1,000 live births and fetal deaths)
by Years of Education, Arizona 2009 (n=462)*

rate per 1,000

6.0

5.8
4.5

5.0
4.0
3.0
2.0
1.0
0.0
12 years or less

13 years or more

*excludes women under 19 years of age and those with unknown years of education
Source: Arizona Fetal Death Certificates, 2009

*

p<0.0001 (CI:0.40 – 2.2)

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 trimester of entry into prenatal care for both women delivering stillbirths
and women delivering live births in 2009. Delivery status (stillbirth or live birth) was not
associated with first trimester prenatal care. However, no prenatal care was strongly
associated with delivery outcome.*

90%
80%

Figure 5. Percent of Women Delivering a Live Birth or Stillbirth
by Start of Prenatal Care*, Arizona 2009
80.0% 80.4%

70%
60%
50%
40%
30%
20%

11.4%

14.4%

10%

2.6% 3.4%

6.0%

1.8%

0%
1st Trimester

2nd Trimester
Stillbirth

3rd Trimester

No Prenatal Care

Live Birth

*excludes missing records
Source: Arizona Birth and Fetal Death Certificates, 2009

*

Chi-square=47.232(1), p<0.0001

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 also been 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 2009 stillbirth cohort (n= 493 smoking responses; n= 493 drinking
responses) and live birth cohort (n= 92,391 smoking responses; n= 92,083 drinking
responses). The Arizona fetal death certificate does not contain information about cigarette
or alcohol use by trimester which limits the analysis for use of these substances to any
time during pregnancy. Figure 6 shows the percentage of women who reported smoking
cigarettes or drinking alcohol during pregnancy for the 2009 stillbirth and live birth cohorts.

Figure 6. Percent of Women Reporting Cigarette Use or Drinking
Alcohol During Pregnancy* by Delivery Status, Arizona 2009
10.0%
9.0%
8.0%
7.0%

6.7%

6.0%
4.8%

5.0%
4.0%
3.0%
2.0%

1.4%
0.5%

1.0%
0.0%
Stillbirth
Smoking

Live Birth
Drinking

*analysis restricted to those women responding "yes" or "no" to each question
Source: Arizona Birth and Fetal Death Certificates, 2009

Approximately seven percent of women who had a stillbirth reported smoking and 1.4
percent reported drinking while pregnant. Only 4.8 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 (7.3 per 1,000 live births + stillbirths) was not significantly greater than the rate
of stillbirth among non-smokers (5.2 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
7

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, 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

60%

Figure 7. Percent of Stillbirths by Gestational Age
Arizona 2009 (n=508)*
52.0%

50%
40%

32.1%

30%
20%

14.4%

10%
1.6%
0%
20-27 weeks
(n=264)

28-36 weeks
(n=163)

37-40 weeks
(n=73)

41 or more weeks
(n=8)

*excludes records with missing gestational age
Source: Arizona Fetal Death Certificates, 2009

Similar to national statistics3, 52 percent of stillbirths in Arizona occurred prior to 28 weeks
gestation and 14.4 percent were „at term‟ (37-40 weeks gestation). Although gestational
age is determined by physician‟s estimate (clinical estimate) and not reported by 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 as stillbirths instead
of miscarriages.

8

Figure 8 shows the reported weight of stillbirths from the 2009 cohort. It is evident from
Figure 8 that approximately 40 percent of stillbirths delivered in 2009 were reported to
weigh between 350 to 1,499 grams, 16.4 percent weighed between 1,500 and 2,499
grams, and 17.4 percent weighed 2,500 to 3,999 grams. Macrosomic stillbirths (4,000
grams or more) comprised 2.5 percent of the cohort. Another 23.7 percent were reported
to weigh less than 350 grams.

Figure 8. Percent of Stillbirths by Delivery Weight
Arizona 2009 (n=511)

2.5%
17.4%

23.7%
Less than 350 grams (n=121)
350 to 1,499 grams (n=204)

16.4%

1,500 to 2,499 grams (n=84)
2,500 to 3,999 grams (n=89)

39.9%

4,000 or more grams (n=13)

Source: Arizona Fetal Death Certificates, 2009

County of Occurrence and Frequency of Autopsy
Although the majority of stillbirths in 2009 continued to occur among female residents of
urban counties, rates of stillbirth varied more widely in rural counties (0.0 to 11.2 per
1,000) compared to urban counties (5.3 to 5.5) due to the relatively small size of rural
populations (appendix B). In 2009, 61 percent of those stillbirths were delivered by
residents of Maricopa County (n=312), 13 percent in Pima county (n=68), and the
remainder of stillbirths with known maternal residence occurred in 11 other counties
(n=131).
9

Fetal autopsies are the most useful diagnostic procedure for information on the cause of
death.3,9 However, only nine percent (n=45) of stillbirths with complete data in 2009 received
an autopsy. The proportion of stillbirths receiving an autopsy in 2009 has decreased from a
high of 16.4 percent in 2004. Additionally, the quality of data has declined over the reported
autopsy field. Less than one percent of cases were coded as “unknown” in 2003, but six
percent (n=32) were coded as “unknown” in 2009.
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 (8.5 percent
compared to 12.1 percent), the difference was not significant.

100%

Figure 9. Percent of Stillbirths Receiving Autopsy
by Urban and Rural Areas*, Arizona 2009 (n=511)
89.0%

90%
80%

65.7%

70%
60%
50%
40%

26.0%

30%
20%
10%

8.9%

8.3%
2.1%

0%
urban (n=427)
Autopsy

rural (n=84)
No Autopsy

Unknown

Source: Arizona Fetal Death Certificate, 2009
*Urban areas include Maricopa, Pima, Pinal and Yuma Counties. All other counties are considered rural.

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, the
percentage of stillbirths delivered by non-Hispanic women that received an autopsy was 11.5
percent compared to six percent of stillbirths delivered by Hispanic women. Greater
proportions of stillbirths were autopsied for White (12.1 percent), and African American (15.4
percent) women than for stillbirths delivered by American Indian women (7.1 percent), and
10

Asian or Pacific Islander (zero percent). 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 2009, only 9.9
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 (8.9
percent) and those occurring very early term.
Figure 10 shows the percentage of stillbirths that were autopsied by reported gestational
weight. In 2009 there was no discernible trend in autopsy by weight of stillbirth.

16%

Figure 10. Percent of Stillbirths Autopsied by Delivery Weight
Arizona 2009

14%
12%

10.8%
9.5%

10%
8%

7.9%

8.1%

8.3%

6%
4%
2%
0%
Less than 350 350 to 1,499 1,500 to 2,499 2,500 to 3,999 4,000 or more
grams (n=9) grams (n=21) grams (n=6) grams (n=8) grams (n=1)
Source: Arizona Fetal Death Certificates, 2009

*

includes only records with complete data over autopsy field.

11

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 only used onethird of the time to ascertain the cause of fetal demise in Arizona.
Figure 11. Percent of Autopsies Used to Determine Cause of
Death among those Stilbirths Receiving Autopsy
Arizona 2009 (n=45)
50%

45%
37.8%

40%
35%

33.3%
28.9%

30%
25%
20%
15%
10%
5%
0%
Autopsy used (n=15)

Autopsy not used (n=17)

Unknown (n=13)

Source: Arizona Fetal Death Certificates, 2009

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 2009 there were 58 distinct ICD-10
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.

12

Figure 12 shows causes of stillbirths for the 2009 reporting period.* As is true in many studies
on the causes of stillbirths3, the cause of death was unknown in 46 percent of stillbirths for
this time period. The lack of a definitive cause of death is often the result of insufficient
medical knowledge regarding the etiology of stillbirth.** Additionally, eight percent of the
stillbirths had an inappropriate ICD-10 code, seven percent of the stillbirths had an invalid
ICD-10 code, and two percent of the stillbirths did not have an ICD-10 code listed under
cause of death. The remaining 36 percent of fetal deaths had ICD-10 codes indicating a valid
and specific cause of deaths.

Figure 12. Percent of Stillbirths by Recoded Cause of Death*
Arizona 2009 (n=511)

2.4% 0.1%
Unknown (n=236)

6.9%
7.8%

Valid and Specific (n=184)

46.5%

Inappropriate ICD-10 Code (n=40)
Invalid ICD-10 Code (n=35)

36.2%

Missing ICD-10 Code (n=12)
Other Residual Causes (n=4)

*recoded ICD-10 groupings developed by Dr. Mike Clement of the Arizona Perinatal Trust in 2006
Source: Arizona Fetal Death Certificates, 2009

*

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 which is still used by Arizona.
**
As per correspondence with Donna Hoyert, PhD, Division of Vital Statistics, NCHS, CDC, on November 25th, 2008

13

Of the stillbirths with a known and specific cause of death (Figure 13), the most common
causes were cord problems (31.5 percent), malformation (30 percent), and placental
disorders (22 percent). None of the other recoded causes of death accounted for more than
six percent of stillbirths with valid ICD-10 data.
Figure 13. Specific and Valid Causes of Stillbirth
Arizona 2009 (n=181)
Cord Problems (n=58)

31.5%

Malformation (n=57)

30.1%

Placental Disorders (n=41)

22.3%

Cardiovascular (n=11)

6.0%

Hydrops Fetalis or…
Hypertension (n=5)

2.7%
2.7%

Inflamation/Infection (n=2)

1.1%

IUGR* (n=2)

1.1%

Hypoxia (n=2)

1.1%

Intercranial Hemorrage (n=1)

0.5%
0%

10%

20%

30%

40%

50%

*Intrauterine growth restriction refers to a fetus whose weight is below the 10th percentile for its gestational age.
Source: Arizona Fetal Death Certificates, 2009

Figure 14 shows the top three reported causes of death by gestational age categories.

70%

Figure 14. Top Three Causes of Stillbirth by Length of Gestation
Arizona 2009 (n=179)*

60%

50.0%

50%
36.7%

40%
30%

30.4%

35.3%

30.9%

21.5%

17.7%

20%

18.8%

15.6%

10%
0%
Less than 28 weeks
Cord Problems

28 through 36 weeks
Malformation

37 weeks and greater

Placental disorders

*two records with specific causes of death were missing gestational weight and are not included in this analysis
Source: Arizona Fetal Death Certificates, 2009

14

Forty 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 (50 percent)
accounted for the greatest proportion of deaths, while malformation (36.7 percent) was the
most common cause of death for very early term stillbirths.

Study Limitations
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 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 511 cases reported in these files,
three 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 508 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 14 percent of cases.
When using date of last menses to measure gestational age for those records with complete
and reliable data, approximately four percent (n=17) of stillbirths were less than 20 weeks old
and nearly one-third of these cases (n=5) also had reported delivery weights under 350
grams. These cases would not have been 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. Twenty-four percent (n=121) of stillbirths in the data set were reported to weigh less
than 350 grams, but all were of an appropriate gestational age (> 20 weeks) to be included in
this report.

*

Chi-square 0.491(1) p=0.48

15

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
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 findings 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 valid coding of up to 85 percent of fetal
deaths.11,12 Classification systems that rely on data collected in the 2003 U.S. Standard Fetal
Death Certificate would improve the validity of the underlying causes of stillbirth.

16

Appendix A
Total Number of Stillbirths*
ARIZONA
Apache
Cochise
Coconino
Gila
Graham
Greenlee
Maricopa
Mohave
Navajo
Pima
Pinal
Santa
Cruz
Yavapai
Yuma
La Paz
Unknown

Rate of Stillbirths**

2004

2005

2006

2007

2008

2009

2004

2005

2006

2007

2008

2009

505
5
10
7
2
2
1
339
11
12
54
14
4

532
7
14
9
3
2
1
330
19
15
68
21
5

543
4
12
14
11
2
0
351
15
13
79
17
3

583
9
13
9
4
0
0
360
17
15
88
39
0

544
8
7
7
6
5
1
350
9
15
73
33
6

511
2
16
12
8
2
0
312
14
11
68
29
3

5.4
3.7
5.5
3.4
3.0
4.4
9.6
5.6
5.0
6.7
4.1
4.5
4.9

5.5
5.4
7.9
4.3
4.6
4.4
10.0
5.3
8.4
7.8
5.2
5.7
6.4

5.3
3.4
6.6
6.8
16.5
3.7
0.0
5.3
6.1
6.9
5.7
3.8
4.0

5.6
7.7
7.0
4.2
5.7
0.0
0.0
5.4
6.9
7.4
6.3
7.3
0.0

5.5
6.6
3.9
3.5
8.5
7.7
7.6
5.6
3.9
7.7
5.4
5.7
7.5

5.5
1.6
8.7
6.3
11.2
3.1
0.0
5.4
6.3
5.8
5.3
5.4
3.9

15
25
4
0

7
30
0
0

10
12
0
0

14
14
0
0

3
18
2
1

16
18
0
0

7.4
7.5
17.1
NA

3.3
9.0
0.0
NA

4.2
3.6
0.0
NA

5.7
4.3
0.0
NA

1.4
5.3
8.1
NA

7.7
5.5
0.0
NA

*

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 stillbirths.

Note: Urban counties include Maricopa, Pima, Pinal and Yuma. All other counties are considered
rural.
Source: Arizona Birth and Fetal Death Certificates, 2004-2009

17

Appendix B

Stillbirths: Arizona and the U.S.
Characteristic

Arizona 2009

U.S. 2005*

Total number

511

25,894

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

5.5

6.2

11.7

11.1

American Indian or Alaskan Native

7.4

6.2

Asian or Pacific Islander

3.2

4.8

Hispanic or Latina

5.3

5.4

White non-Hispanic

4.9

4.8

Triplet or more

16.1**

27.2

Twin

12.1

16.1

Singleton

5.3

5.9

< 15 years old

0.0

12.2

15 thru 17 years old

6.1

7.5

20 thru 24 years old

4.6

5.9

25 thru 29 years old

4.7

5.5

30 thru 34 years old

5.3

5.8

35 thru 39 years old

8.0

7.3

40 thru 44 years old

11.8

11.1

45 years and older

11.6**

15.5

Rate by race:
Black or African American

Rate by Plurality:

Rate by maternal age:

*

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

18

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 Maternal-Fetal
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;2005:95:22132217.
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. 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;2005:331:1113-1117.
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.

19

To obtain further information, contact:
Arizona Department of Health 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

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