|
|
 |
|
|
Chapter
III Risk Factors for Poor Birth Outcomes
Eliminating
racial/ethnic disparities in perinatal outcomes
requires thorough knowledge of their causes.
Researchers suggest that several factors contribute
to racial/ethnic disparities in perinatal health:
stress, environment, genetics, economic resources
and socioeconomic status, health behavior, access
to and availability of health care services,
and quality of health care (Hogan et al. 2001).
In this chapter, evidence on the behavioral,
biological, and social risk factors for poor
perinatal outcomes in the context of racial/ethnic
disparities is presented. Table III.1 lists
the risk factors discussed. In categorizing
risk factors as behavioral, biological, and
social, the interdependent nature of risk factors
between and within categories is recognized.
For example, a biological risk factor such as
depression can lead to behavioral risk factors,
such as alcohol use and smoking during pregnancy.
As a result, the risk factors in relationship
to each other are discussed whenever possible.
The inter-related quality of these risk factors
also makes it challenging to pinpoint the direct
contribution of each factor to poor birth outcomes.
Adding to this challenge is women' s possible
self-selection to certain risk groups (such
as those receiving late or no prenatal care).
Therefore, no attempt is made to draw direct
causal relationships between risk factors and
adverse birth outcomes, but a link between the
two, acknowledging the influence of other factors
is illustrated.
This
chapter provides insight into areas where targeted
maternal and child health interventions through
programs, such as Healthy Start, could help
reduce racial/ethnic disparities in birth outcomes.
Therefore, issues related to socioeconomics,
clinical practice, genetics, and access to health
care are not directly discussed. However, these
issues in relation to the risk factors presented
in the chapter is acknowledged. For example,
some behavioral factors, such as getting early
prenatal care and obtaining well child visits,
can be influenced by a woman' s ability to access
this care and her knowledge about such care.
Despite these multiple influences on a woman'
s ultimate behavior, this discussion emphasizes
the need for interventions and systems to encourage,
support, and reinforce positive perinatal behaviors.
 [D]
BEHAVIORAL
RISK FACTORS
PREVENTIVE
BEHAVIORS
Prenatal Care
The
American College of Obstetricians and Gynecologists
recommends that all pregnant women initiate
prenatal care in the first trimester and continue
care at specified intervals throughout pregnancy
(Beck et al. 2002). Lack of prenatal care is
associated with an increased risk of preterm
birth, low birthweight, and infant death (Beck
et al. 2002). From 1995 to 2002, women who had
no prenatal care consistently had approximately
five times the risk of infant death of women
who received prenatal care during any trimester
(Table III.2).
 [D]
The
link between prenatal care and adverse birth
outcomes is not fully understood, but research
indicates that early, regular prenatal care
is associated with a decreased risk of poor
birth outcomes (Vintzileos et al. 2002a, 2002b).
Examination of trimester when prenatal care
began by race/ethnicity demonstrates that Whites
and Asian/Pacific Islanders had the highest
percentages of women who initiated prenatal
care in the first trimester; American Indian/Alaska
Natives and Blacks had the highest proportions
of women who received late or no prenatal care
in 2002 (Table III.3).
The
racial/ethnic pattern of late or no prenatal
care parallels infant mortality rates; Blacks
and American Indian/Alaska Natives have both
the highest rates of late or no prenatal care
and the highest rates of infant mortality. When
infant mortality is stratified by when trimester
of pregnancy when prenatal care began, however,
Blacks and American Indian/Alaska Natives have
higher rates of infant mortality, regardless
of timing of prenatal care (Table III.4). This
suggests that differences in prenatal care only
partially explain differences in infant mortality.
Regardless of the causal link, prenatal care
offers an opportunity for early risk assessment,
intervention, and monitoring among those at
risk for adverse birth outcomes.
 [D]
Folic
Acid Use
Neural tube defects (NTD) occur in approximately
one per 1,000 births in the United States. It
is estimated that adequate levels of folic acid
one month before conception and through the
first trimester of pregnancy could prevent 50
to 70 percent of these defects (Centers for
Disease Control and Prevention 1999a). NTDs
were responsible for 1.4 percent of all infant
deaths in 2000 (Williams et al. 2003). In addition,
they are associated with spontaneous abortions
and low birthweight/prematurity. Between 1996
and 1998, 74 percent of NTD-specific deaths
were low birthweight, and 58 percent were preterm
(Davidoff et al. 2002).2
The
Healthy People 2010 goal is for 80 percent of
women of child-bearing age to consume at least
400 micrograms of folic acid daily. Approximately
only one in three women in the United States
consume this amount (American Academy of Pediatrics
1999, Centers for Disease Control and Prevention
2005). Folic acid use was highest among White
non-Hispanic women and lowest among Black non-Hispanic
women
(Centers
for Disease Control and Prevention 2002a). Despite
having lower levels of folic acid use, Black
women had a lower NTD-specific infant mortality
rate than White, Asian/Pacific Islander, and
American Indian/Alaska Native women (Figure
III.1). Black women had a rate of NTD-specific
infant death of 8.6 per 100,000 live births,
compared to 11.6, 9.8, and 11.5 for White, Asian/Pacific
Islander, and American Indian/Alaska Native
women, respectively. Infant mortality rates
do not take into account spontaneous abortions
that could be associated with NTD (Petrini et
al. 2002). Therefore, the discrepancy in NTD-specific
mortality rates between Blacks and Whites, in
particular, could be connected to Black women
having a higher rate of spontaneous fetal loss
than White women; in 1999, 19.4 of 1,000 Black
non-Hispanic women experienced fetal loss, compared
to 14.8 of 1,000 White non-Hispanic women (Ventura
et al. 2003). Further research is needed to
examine this potential explanation.
 [D]
Periodontal
Care
Studies have shown that pregnant women with
periodontal disease may be up to seven times
more likely to deliver a preterm/low birthweight
infant than those without such disease (American
Acad-emy of Periodontology 2004). Hormone changes
during pregnancy, especially in the second and
third trimesters, can cause a greater reaction
to dental plaque, resulting in increased swelling,
bleeding, and redness of the gums leading to
periodontal disease.The disease may contribute
to as many as 45,000 (18 percent) of the preterm
births that occur every year (Offenbach et al.
1996). This is more than the preterm births
attributed to alcohol consumption and tobacco
use combined.
Lower
socioeconomic and minority status are associated
with untreated periodontal disease. For example,
Blacks and American Indian/Alaska Natives have
a higher prevalence of periodontal disease than
Whites, with Blacks having the highest rate
of periodontal disease of all races/ethnicities
(Skrepcinski andNiendorff 2000).
In addition, the disparity in the rate of disease
between White and Black populations has increased
since 1971 (Borrell et al. 2002). In general,
Blacks are less likely to use dental services,
which may increase the rate of periodontal disease
or exacerbate its severity (Doty and Weech-Maldonado
2003).
Infant
Sleep Position
SIDS is the leading cause of postneonatal mortality
and the third leading cause of all infant mortality
in the United States, accounting for approximately
eight percent of all infant deaths (Mathews
et al. 2004). Infant sleep position and sleep
environment have been identified as modifiable
factors that can help reduce the risk of SIDS.
Although SIDS declined almost 35 percent between
1995 and 2002 to 57.1 per 100,000 live births,
experts are concerned about disparities in the
rate of SIDS among different racial/ethnic groups
(Table III.5) (Centers for Disease Control and
Prevention 1996). As noted in Chapter II, American
Indian/Alaska Native infants are more than twice
as likely as White infants to die of SIDS, and
Black infants have a SIDS rate more than twice
the national average and that of Whites. The
rate of SIDS among Blacks has also decreased
at a lower rate than in the overall population.
Despite having a SIDS rate below that of Blacks
and American Indian/Alaska Natives for all years
between 1997 and 2001, Puerto Ricans were the
only racial/ethnic group for which the rate
of SIDS increased during this time period.
 [D]
Variations
in infant sleep position may explain some of
the disparity in the SIDS rate. A study conducted
between 1994 and 1998 showed that 32 percent
of Black mothers, compared to 17 percent of
other mothers, place their infants to sleep
in the prone position (on the stomach) (Willinger
et al. 2000). Black infants who die of SIDS
also have a higher prevalence of bed sharing
and using bed surfaces other than those specifically
designed and approved for infant use, as well
as other risk factors for SIDS, such as smoking
in the home, than White infants (Unger et al.
2003). Among American Indian/Alaska Natives,
16 to 24 percent put their babies to sleep on
their stomach (U.S. Department of Health and
Human Services 1998). American Indian/Alaska
Native infants also have an increased risk of
SIDS because their mothers are more likely than
other mothers to binge drink during the first
trimester of pregnancy; binge drinking increases
the risk of SIDS eightfold among American Indian/Alaska
Natives (Iyasu et al. 2002).
The
Back to Sleep campaign, started in 1994,spreads
awareness about the importance of sleepposition
in the reduction of SIDS and racial/ethnic disparities
in SIDS. Providers also play an important role
in SIDS reduction by influencing the behavior
of new mothers. In examining the relationship
between information sources and SIDS risk behavior,
specific instruction by a nurse or doctor in
the hospital about how to properly place the
infant for sleep positively influenced behavior
after the mother left the hospital (Rasinski
et al. 2003).
Breastfeeding
Breastfeeding
provides nutritional and immunological benefits
to the baby during and after the first year
of life (U.S. Department of Health and Human
Services 2000b). The American Academy of Pediatrics
and the World Health Organization recommend
that women breastfeed their infants for at least
1 year to reduce the incidence of acute illnesses
(such as diarrhea, ear infections, pneumonia,
and meningitis) and chronic diseases (such as
SIDS, obesity, childhood leukemia, and asthma)
(American Academy of Pediatrics 2004; Wolf 2003).
Data from the 1988 National Maternal and Infant
Health Survey of women with a live birth or
infant death in 1988 showed that infants who
were ever breastfed3
had a 21 percent decreased
odds of postneonatal death, compared to infants
who were not ever breastfed (Chen and Rogan
2004). After controlling for demographic and
socioeconomic characteristics, the study also
found that breastfeeding reduced the odds of
postneonatal deaths regardless of race. However,
the magnitude of breastfeeding’s impact
on postneonatal death differed between Black
and non-Black populations. Breastfeeding decreased
the odds of postneonatal death by 31 percent
among Black infants, while it reduced the odds
by 19 percent among non-Black infants.
Between
1971 and 2001, breastfeeding rates increased
in the early postpartum period from 25 percent
to 70 percent and at 6 months postpartum from
5 percent to 33 percent (Ryan et al. 2002).
However, these breastfeeding rates are still
below Healthy People 2010 objectives of 75 percent
of women breastfeeding in the early postpartum
period and 50 percent at 6 months (U.S. Department
of Health and Human Services 2000a). The breastfeeding
rate at 1 year in 2001 was 12 percent, which
also is lower than the Healthy People 2010 goal
of 25 percent at 1 year (Li et al. 2003; U.S.Department
of Health and Human Services 2000a).
In
particular, Black women have consistently lower
rates of breast feeding than do White and Hispanic
women. A report based on the 2004 National Immunization
Survey indicated that 71.5 percent of non-Hispanic
White children were ever breastfed in comparison
to 50.1 percent of non-Hispanic Black children
(Centers for Disease Control and Prevention
2006). Continuing to breastfeed until at least
6 months of age was also higher among White
non-Hispanic women (53.9 percent) than Black
non-Hispanic women (43.2 percent). In addition,
the 1988-1994 National Health and Nutrition
Examination Survey of women with children ages
12 to 71 months found that 26 percent of Black
women had ever breastfed their infant, compared
to 60 percent of White women and 55 percent
of Mexican American women (Li and Grummer-Strawn
2002). Results from the 2001 Ross Laboratory
Mothers Survey of women with infants ages 6
to 12 months and the 2001 National Immunization
Survey of women with children ages 19 to 35
months showed that Black women had lower rates
than White and Hispanic women of ever breastfeeding
in hospital, at 6 months, and at 12 months (Ryan
et al. 2002; Li etal. 2003).
According
to results from the 1988 National Maternal and
Infant Health Survey, Black women in the Special
Supplemental Nutrition Program for Women, Infants,
and Children (WIC) were also less likely than
White women to receive breastfeeding advice
from WIC counselors and more likely to receive
bottle-feeding education from them (Beal et
al. 2003). The disparity in breastfeeding behavior
between Blacks and Whites who received breastfeeding
advice was smaller than that between Blacks
and Whites who did not receive advice, suggesting
that increased education may help narrow the
gap in breastfeeding practices.
Well-Child
Care (Up to Two Years Old)
Health
maintenance and preventive health care are important
to a child’s well-being after birth. Due
to a combination of medical advances and public
health measures, the overall health status of
children in the United States has improved considerably
during the past several decades. Mortality between
1950 and 1987 was reduced by 63 percent for
children ages 1 to 4, and well-child visits
promoting vaccinations and other preventive
health measures significantly contributed to
this improvement (Middleton and Schroeder 2002).
 [D]
The
American Academy of Pediatrics and the American
Board of Family Practice recommend 11 well-child
visits from birth to age 2 on the following
schedule: at birth; at one week; and at 1, 2,
4, 6, 9, 12, 15, 18, and 24 months. Childhood
vaccinations given during these visits have
had a major impact on the reduction and elimination
of many causes ofchildhood morbidity and mortality.
For example, smallpox has been eradicated, and
polio has been eliminated in the United States.
Measles and Haemophilus influenza type b (Hib)
have also been reduced to record low numbers
(Centers for Disease Control and Prevention
1999b).
Currently,
the CDC recommends that all infants finish the
series of vaccinations shown in Table III.6
by age 2 (Centers for Disease Control and Preven-tion
2004c). In 1999, 73 percent of children ages
19to 35 months met these recommendations (TableIII.6,
last row). Compliance with vaccination varies
by race/ethnicity; in general, White non-Hispanicand
Asian/Pacific Islanders had slightly higher
rates of vaccination than Black non-Hispanics
and American Indians/Alaska Natives. Researchers
also found that racial/ethnic disparities in
childhood vaccination were not driven by socioeconomic
status; regardless of income level, Black non-Hispanics
had the lowest rates of vaccination for DTP,
polio, MMR, and hepatitis B compared to other
populations (Barker and Lumen 2001; Lumen et
al. 2001). They also had the lowest completion
rate of the vaccination series. No racial/ethnic
group has met the Healthy People 2010 objective
to have 90 percent of all children ages 19 to
35 months complete the vaccination series which
indicates that there is room for improvement
for all groups (U.S. Department ofHealth and
Human Services 2000a).
Interconceptional
Care
The
IOM notes, “One of the best protection
savailable against low birthweight and other
poor pregnancy outcomes is to have women actively
plan for pregnancy, enter pregnancy in good
health with as few risk factors as possible,
and be fully informed about her reproductive
and general health” (Institute of Medicine
1985). Experts suggest that, to restore the
maternal nutritional resources necessary for
a healthy pregnancy, it is essential to have
one or more years between the birth of one infant
and the conception of another (Klerman et al.
1998). Studies have shown that nearly a quarter
of pregnant women have an interpregnancy period
of less than a year (Zhu et al.2001; James et
al. 1999; Russo et al. 1993). Short interpregnancy
intervals are associated with late entry into
prenatal care, low birthweight, premature birth,
and other poor pregnancy outcomes. Williamset
al. (2003) found that, compared to infants born
following an interpregnancy interval of less
than 6 months, infants born to women who became
pregnant 18 to 59 months after a prior birth
had a lower risk of dying, being born preterm,
being small for gestational age, or having low
birthweight. Another study showed that infants
born to women who become pregnant less than
6 months after delivery have three times the
risk of infant death due to intentional injury,
a 74 percent increased risk of unintentional
injuries, and a 55 percent increased risk of
SIDS (Easton 1999). Black and Native American
women have the highest rates of short interpregnancy
intervals, compared to other racial/ethnic groups.
From 1981 to 1989, 30 percent of Native American
pregnancies were conceived less than a year
after a prior birth, compared to 19 percent
of pregnancies among White non-Hispanics (Khoshnood
et al. 1998). Studies have shown that Black
women are twice as likely as White women to
have an interpregnancy period of 6 months or
less (James et al. 1999; Zhu et al. 2001). Even
among Black and White women with interpregnancy
periods of 6 months or less, Blacks still had
a higher rate of pretermbirth than Whites. Although
this suggests that other risk factors may act
in conjunction with a short interpregnancy period
to cause disparities in birth outcomes, having
an adequate interpregnancy period may protect
against poor birth outcomes for all women.
Risky
Behaviors
Maternal
Smoking
Research
suggests that infants born to women who smoke
cigarettes during pregnancy have a 40 percent
higher risk of death in their first year than
infants whose mothers did not smoke (Salihu
et al.2003). In the United States, an estimated
five percent of infant mortality is attributable
to smoking, with variation among different races
and ethnicities. Smoking during pregnancy contributes
to many adverse outcomes, including ectopic
pregnancy, fetal death, stillbirth, spontaneous
abortion, low birthweight, preterm delivery,
SIDS, intrauterine growth retardation, placenta
previa, abruptio placenta, and premature rupture
of membranes. Morbidity and mortality increase
with the amount of cigarettes consumed prenatally
(Salihu et al. 2003).
Although
the overall rate of smoking during pregnancy
declined 33 percent between 1990 and 1999, more
than 10 percent of women reported smoking during
pregnancy in 1999 (Figure III.2). Rates of reported
smoking were the highest among American Indian/Alaska
Natives, who also had the lowest rate of decrease
in reported smoking during pregnancy between
1990 and 1999. All other races and ethnicities
reduced the reported rate of smoking during
pregnancy by more than 20 percent, while American
Indian/Alaska Natives reduced their reported
rate by 11 percent.
The
high rate of smoking during pregnancy among
American Indian/Alaska Natives may contribute
to their high rate of SIDS. However, due to
the interaction of smoking with other factors
that contribute to adverse birth outcomes, the
direct impact of smoking during pregnancy on
infant mortality is difficult to tease out.
For example, why does smoking during pregnancy
differentially affect infant survival across
racial/ethnic groups? Smoking among Whites is
associated with a 85 percent increased risk
of infant mortality, while it is associated
with an increased risk of 53, 147,and 57 percent
among Blacks, Asian/Pacific Islanders, and American
Indian/Alaska Natives, respectively (Figure
III.3). It is difficult to understand the direct
effect of smoking on birth outcomes, but it
is clear that, for all racial/ethnic groups,
women who smoked during pregnancy had higher
rates of infant mortality than women who did
not smoke.
In
addition to the adverse effect that smoking
during pregnancy has on infants, smoke exposure
after birth also has negative impacts on infant
health.
 [D]
 [D]
Research
has shown that secondhand cigarette smoke exposure
increases the risk of respiratory illnesses
among infants. Such illnesses, including asthma
and lower respiratory tract infections, can
lead to respiratory distress, the sixth leading
causes of infant mortality in 2002 (DiFranza
and Lew 1996). Although the overall rate of
secondhand smoke exposure among infants has
not been precisely measured, examination of
smoking behavior by race shows that American
Indian/Alaska Natives have the highest rate
of tobacco use in comparison to other races
and ethnicities (Table III.7).
To
encourage pregnant and non-pregnant women of
all races/ethnicities to stop smoking, the U.S.
Public Health Service sponsors a best practice
guideline called the “5 A’s”
(U.S. Surgeon General 2005). The “5 A’s”
guideline includes five steps to identify tobacco
users and implement appropriate interventions
based on their willingness to quit. The five
major steps to intervention are: (1) ask about
smoking status; (2) advise in a clear, strong,
and personalized manner why the person should
quit; (3) assess the willingness of the person
to quit; (4) assist the person using counseling
and pharmacotherapy if they are willing to quit;
and (5) arrange for follow-up with the person.
This guideline provides a conceptual framework
for interventions to motivate pregnant and non-pregnant
women to quit smoking.
 [D]
Alcohol
and Other Drug Use During Pregnancy
Drinking
alcohol during the first seven months of pregnancy
is associated with preterm delivery and low
birthweight (Lundsberg et al. 1997). Though
the risk of having poor birth outcomes rises
with increasing alcohol use, any fetal alcohol
exposure puts a fetus at risk for developing
fetal alcohol syndrome.4
Fetal alcohol exposure is the
leading cause of preventable birth defects and
developmental disorders in the United States.
As many as 1 in 100 children in the United States
are believed to be affected by fetal alcohol
exposure, although fetal alcohol syndrome is
100 percent preventable (Meschke et al. 2003).
Data
from the CDC’s Birth Defects Monitoring
Program showed that fetal alcohol syndrome increased
fourfold between 1979 and 1992, to 3.7 cases
per 10,000 live births (Centers for Disease
Control and Prevention 2003a). In 1992, Behavioral
Risk Factor Surveillance System data indicated
that more than 12.4 percent of women reported
drinking alcohol during pregnancy (Centers for
Disease Control and Prevention 2002b). Since
1992, the prevalence of reported alcohol use
among pregnant women has increased slightly,
to 12.8 percent in 1999, and decreased slightly,
to 12.5 percent in 2001 (Centers for Disease
Control and Prevention 2002b; Floyd and Sidhu
2004). According to data reported on birth certificates,
alcohol use during pregnancy was more frequent
among American Indian/Alaska Natives than any
other racial/ethnic group (Table III.8); they
had three times the alcohol use rate during
pregnancy of any other racial/ethnic group.
Black and White women had the second-highest
rate of alcohol use, while Hispanics had the
lowest rate.
 [D]
The
rate of fetal alcohol syndrome among different
racial/ethnic groups follows a pattern similar
to that of alcohol use among these groups during
pregnancy. In 1994, the CDC’s National
Institute of Alcohol Abuse and Alcoholism reported
that American Indian/Alaska Natives had more
than fou rtimes the rate of fetal alcohol syndrome
(30 cases per 10,000 births) than any other
group; Black women had the second-highest rate
(6 cases per 10,000 births) (Meschke et al.
2003). In contrast,Whites had an incidence of
0.9 cases per 10,000 births, followed by Hispanics
(0.8 cases per 10,000 births) and Asian/Pacific
Islanders (0.3 cases per 10,000 births).
Use
of other substances, such as cocaine, marijuana,
or other illicit drugs5,
during pregnancy is another risk factor for
preterm, low birthweight, and very low birthweight
births (Blatt et al. 2000).Women who use drugs
such as cocaine during pregnancy have more than
twice the odds of delivering a preterm, low
birthweight, or very low birthweight baby as
pregnant women who do not use any substances
(Blatt et al. 2000; March of Dimes 2004). Women
who use cocaine during pregnancy are also twice
as likely as women who do not to have an infant
die of SIDS and five times more likely to have
a baby with a birth defect. Substance users
are more likely than non-users to miss prenatal
care appointments (Funai et al. 2003).
According
to the Substance Abuse and Mental Health Services
Administration’s 2000 and 2001 National
Household Survey on Drug Abuse, 3.7 percent
of women reported using illicit drugs during
pregnancy (U.S. Department of Health and Human
Services 2002). Of the women who reported any
illicit drug use during pregnancy, 70 percent
reported using marijuana, and 8 percent reported
using cocaine. Of those who used illicit drugs
during pregnancy, more than half also smoked
cigarettes or drank alcohol (Shahul and Gfroerer
2003).
Drug
use varies by race/ethnicity, with non-White
women being almost twice as likely as White
women to use illicit drugs (Kelly et al. 2002).
Drug use during pregnancy has a differential
impact on racial/ethnic groups; Black women
who report illicit substance use had approximately
a twofold increase in odds of delivering a preterm,
low birthweight, or very low birthweight infant,
compared to White women who reported illicit
substance use (Kelly et al. 2002; March of Dimes
2004). This implies that drug use, like smoking,
may be associated with other risk factors for
poor perinatal outcomes.
Adolescent
Pregnancy
Every
year in the United States, more than 800,000
adolescent girls ages 15 to 19 become pregnant
(Ventura et al. 2004). The rate of teenage pregnancy
declined by nearly 10 percent between 1990 and
2000, to 104 pregnancies per 1,000 teenagers.
However, the rate of births to adolescents in
the United States still ranks much higher than
that of most other developed countries, such
as Sweden, France, Canada, and Great Britain
(Darroch et al. 2001). In 2001, there were 43.5
births per 1,000 teenagers in the United States
(Hamilton et al. 2003). Children born to teenagers
have an increased risk of low birthweight, prematurity,
intrauterine growth retardation, congenital
malformations, and infant death (Cunnington
2001). Before controlling for demographic factors,
adolescents have an infant mortality rate 1.6
times that of women older than age 20 (Mathews
et al. 2004). When controlling for race and
ethnicity, White and Asian/ Pacific Islander
teenagers have more than two times the infant
mortality rate of their older counterparts,
while Black and American Indian/Alaska Native
teenagers have rates of infant mortality comparable
to those of their older counterparts; Hispanic
teenagershave 1.4 times the rate of their older
counterparts (Mathews et al. 2004) (Appendix
A, Table A.12). Although these results indicate
that the risk of teenage pregnancy varies by
race, pregnant teenagers are more likely than
pregnant adults to have health behaviors that
lead to poor birth outcomes, regardless of race
(Elfenbein and Felice 2003). For example, they
are less likely to gain adequate weight during
pregnancy, take recommended daily vitamins during
pregnancy, have good eating habits, and seek
prenatal care. They are also more likely to
smoke, drink alcohol, or take drugs and to have
a shorter interpregnancy interval.
Black
teenagers have nearly three times the pregnancy
rate of White teenagers, and Hispanic teenagers
have twice the rate of White teenagers (Ventura
etal. 2004). Infants born to Black teenagers
also have a higher rate of infant mortality
than those born to Whiteteenagers (Figure III.4).
However, Hispanic teenagers have lower rates
of infant mortality than White teenagers, although
they had a higher number of pregnancies. The
high teenage Hispanic birth rate and low infant
mortality rate suggest that the risky behaviors
associated with teenage pregnancy may be mitigated
by other factors, such as culture. For example,
one study found that the Mexican culture had
a positive impact on birth outcomes (Jenny et
al.2001). That study also found that Mexican
American infants born in counties with a high
concentration of Mexican births to women of
Mexican descent that is, a higher exposure to
those with traditional Mexican pregnancy and
child-rearing practices had lower mortality
rates than Mexican American women without such
exposure.
 [D]
BIOLOGICAL/SOCIAL
RISK FACTORS
PERINATAL
DEPRESSION
Untreated
depression during pregnancy is associated with
adverse fetal outcomes. These include spontaneous
abortion, preterm delivery, need for special
neonatal care, increased uterine artery resistance,
small head circumference, low APGA Rscores,
neonatal growth retardation, high cortisol levels
at birth, maternal hypertension, and preeclampsia
(Bonari et al. 2004). Mental illness can affect
a pregnant woman’s functional status and
her ability to obtain prenatal care, eat properly,
take prenatal vitamins, and avoid dangerous
behavior, such as smoking, drinking alcohol,
and using illicit drugs (Bonari et al. 2004;
Zuckerman et al. 1989). In addition, research
has shown that depression can negatively affect
women’s parenting behavior, which has
implications for their children’s health
(Kavanaugh et al. 2006).
Approximately
10 percent of women in the United States have
depressive symptoms during pregnancy. For a
third of these women, it represents their first
episode of major depression (Nonacs and Cohen
2003). The prevalence of depression is higher
among those of low socioeconomic status (Hobfolland
Ritter 1995). Studies have not conclusively
shown a relationship between race and depression
during pregnancy; however, one study found that,
in general, Blacks and Hispanics exhibit elevated
rates of depression compared to Whites (Dunlop
etal. 2003).
STRESS
Stress
during pregnancy has been shown to significantly
increase rates of prematurity and low birthweight
(Copper et al. 1996). According to a study of
2,593 pregnant women performed through the Maternal-Fetal
Medicine Units Network of NIH, women who experience
stress during pregnancy, as measured by a 28-item
Likert scale, are at 1.16 and 1.08 higher odds
for delivering premature and low birthweight
infants, respectively, than women who do not
experience stress during pregnancy. Behaviors
further increasing the risk of prematurity and
low birthweight, such as smoking, substance
abuse, and poor weight gain during pregnancy,
have been reported to be more prevalent among
women who are under stress. In addition, it
has been hypothesized that psychological distress
may cause the secretion of placental corticotropin,
releasing hormone (CRH) that can lead to increased
susceptibility to infections, such as bacterial
vaginosis (Krameret al. 2001).
Exposure
to psychosocial stressors among Black women
in an urban setting has been shown to significantly
increase the occurrence of low birthweight (Orr
et al. 1996). This may be due to factors such
as smoking, substance abuse, prevalence of infection,
or poverty; the exact mechanism is not well
understood.
BACTERIAL
VAGINOSIS
Between
25 and 60 percent of preterm births are attributable
to maternal infections that can lead to infant
morbidity and mortality (Flynn et al. 1999).One
such infection, bacterial vaginosis (BV), is
estimated to be prevalent in 16 percent of pregnant
women and 10 to 30 percent of nonpregnant women
(Hillier et al. 1995). The vaginal flora imbalance
that occurs with BV has been associated with
preterm delivery, low birthweight, premature
rupture of membranes, infection of the chorion
and amnion,and infection of the amniotic fluid.
Women with BV during pregnancy have 1.4 times
the odds of delivering a low birthweight infant
of pregnant women who do not have BV (Hillier
et al. 1995). Preterm delivery among those with
BV can be reduced by 18 percent with antibiotic
prophylaxis (Hauth et al.1995).
Abstaining
from douching and reducing stress during pregnancy
can also significantly decrease BV (Culhane
et al. 2001; Holzman et al. 2001). A study conducted
through the NIH and the CDC’s National
Survey of Family Growth found that Black women
have higher rates than White and Hispanic women
of vaginal douching, and have higher levels
of stress (Copper et al. 1996; Centers for Disease
Control andPrevention 2003b). Both douching
and stress may contribute to pregnant Black
women having three times the prevalence of BV
than White women (Fiscella 2004; Paige et al.
1998).
DOMESTIC
VIOLENCE
Research
conducted in the United States between 1963
and 1995 reveals that up to 20 percent of women
experience domestic violence during pregnancy
(Gazmararian et al. 1996; Coker etal. 2004).
The Pregnancy Risk Assessment Monitoring System
found that, in 17 States surveyed, non-White
women, Hispanic women, and women with Medicaid
were consistently at higher risk of physical
abuse by a husband or partner than their White,
non-Hispanic, and non-Medicaid counterparts
(Centers for Disease Control and Prevention
2002c). Physical abuse at this time can cause
maternal and infant morbidity and mortality.
Research suggests that physical violence during
pregnancy is associated with an increased risk
of antepartum hemorrhage, intrauterine growth
restriction, and perinatal death. Rates of low
birthweight among battered women are also 1.5
to 2.5 times higher than those of nonbattered
women, and rates of preterm birth are 2.5 to
4.0 times higher (Gazmararian et al. 1996;Neggers
et al. 2004). A recent study shows that women
who experienced intimate partner violence during
pregnancy had 3.8 times the odds of antepartum
hemorrhage, 3.1 times the odds of intrauterine
growth restriction, and 8.1 times the odds of
perinatal death of women who did not experience
such violence (Janssen et al. 2003). Physical
abuse during pregnancy has also been found to
be associated with many other risk factors for
infant mortality, such as inadequate prenatal
care, smoking, substance abuse, mental health-related
illness, and short interpregnancy interval (Curry
et al. 1998; Lipsky et al. 2004).
MATERNAL
BIRTHWEIGHT
Maternal
birthweight has been suggested as a determinant
of low infant birthweight and preterm delivery.
Research has shown that women who were themselves
born at a low birthweight or preterm are at
significantly higher risk for having low birthweight
or preterm infants than women who were not low
birthweight or preterm (Coutinho etal. 1997;
Porter et al. 1997; Sanderson et al. 1995; Wang
et al. 1995). One study in Buffalo, New York,
found that, compared to women who weighed 8.0
pounds at birth, women who weighed 6.0 to 7.9
pounds at birth and women who weighed 4.0 to
5.9 pounds at birth had 1.7 and 3.5 greater
odds of de-livering a low birthweight infant,
respectively (Klenbanoff et al. 1984). Sanderson
et al. (1995) found that, although both White
and Black women who were low birthweight themselves
were at higher risk of delivering low birthweight
infants, only Black women who weighed less than
4.0 pounds at birth had significantly greater
risk of delivering a normal birthweight infant
who subsequently died before reaching 1 year
of age. These researchers also demonstrated
that higher prepregnancy weight and height among
women born low birthweight reduced the risk
of low birthweight deliveries. Such results
suggest that, although low maternal birthweight
plays an important role in birth outcomes, other
factors may also mitigate the effects of maternal
low birthweight and prematurity.
Birthweight
may appear to be a genetically transmitted characteristic
because of its seeming intergenerational trend;
however, recurring and similar social and environmental
stress across generations could cause familial
clustering of low birthweight. Lu and Halfron
(2003) examined the link between poor maternal
and infant birth outcomes in the context of
a life course perspective. These researchers
proposed a model where there are critical periods
in a woman’s reproductive life when she
is more vulnerable to risk factors and more
amenable to protective factors. The earliest
of these sensitive periods occurs when the baby
grows in the mother’s womb. Consequently,
if a woman is exposed to risks during her time
in utero, her reproductive potential will be
adversely affected and could result in poor
birth outcomes for herself and her own infant.
In addition, if she continues to experience
other stresses during her life, which are likely
similar to the stresses her mother experienced,
her risk of having an infant with poor birth
outcomes may increase.
This
life course perspective suggests that, because
a woman’s birth outcome and subsequent
pregnancies are influenced by the accumulated
life exposure of her mother and female ancestors
before her, a short period of intervention during
the pregnancy period may not be able to cause
a dramatic decrease in the risk of poor birth
outcomes. According to this model, the racial/ethnic
disparities in birth outcomes we see today can
be explained by many lifetimes of amassed racism,
poverty, and stress. Many social and environmental
risk factors need to be addressed during the
birth, childhood, puberty, and young adulthood
of a woman to influence her infant’s birth
outcome, but intervening during the pregnancy
and interpregnancy period remains key to improving
birth outcomes; targeting women during, and
immediately after, pregnancy is a way to identify
high-risk women and address their risks to improve
outcomes for future generations (Kotelchuck
2003).
2
Reported infant mortality rates do not account
for spontaneous abortions.
3Infants
were considered “ever-breastfed”
if their mother answered “yes” to
the 1988 National Maternal and Infant Health
Survey Question, “Did you ever breastfeed
this infant?”
4Fetal
alcohol syndrome is defined as a group of symptoms
caused by a pregnant woman’s consumption
of alcohol. These symptoms include abnormal
facial features, growth impairment, problems
with learning, memory, attention span, problem
solving, speech, and hearing.
5Illicit
drugs are controlled substances that possess
a high potential for abuse, have no currently
accepted medical use in the United States, and
demonstrate a lack of accepted safety for use
under medical supervision (U.S. Department of
Health and Human Services 2004). Controlled
substances so defined fall under seven headings:
marijuana (marijuana, hashish); stimulants (amphetamines,
cocaine); depressants (barbiturates, tranquilizers,
hypnotics); hallucinogens (acid, PCP); opiates,
or narcotics (heroin, morphine, opium, codeine);
inhalants (sprays, solvents, glue);and designer
drugs (synthetic drugs similar in effect to
stimulants, hallucinogens, and narcotics). To
be used legally and safely, some of these drugs
must be prescribed by a physician. This list
is not comprehensive; omitted substance may
be illegal and may fall under the designation
of controlled substances.
|
Printer-Friendly