Prevalence of risk factors for adverse pregnancy outcomes during pregnancy and the preconception period--United States, 2002-2004.

Abstract

To assess the prevalence of risk factors for adverse pregnancy outcome during the preconception stage and during pregnancy, and to assess differences between women in preconception and pregnancy.
Data from the 2002 and 2004 Behavioral Risk Factor Surveillance System, United States, were used to estimate the prevalence of selected risk factors among women 18-44 in the preconception period (women who wanted a baby in the next 12 months, and were not using contraception, not sterile and not already pregnant) with women who reported that they were pregnant at the time of interview.
Major health risks were reported by substantial proportions of women in the preconceptional period and were also reported by many pregnant women, although pregnant women tended to report lower levels of risk than preconception women. For example, 54.5% of preconception women reported one or more of 3 risk factors (frequent drinking, current smoking, and absence of an HIV test), compared with 32.0% of pregnant women (p < .05). The difference in the prevalence of these three risk factors between preconception and pregnancy was significant for women with health insurance (52.5% in preconception vs. 29.4% in pregnancy, p < .05), but not for women without insurance (63.4% vs. 52.7%, p > .05).
Women appear to be responding to messages regarding behaviors that directly affect pregnancy such as smoking, alcohol consumption and taking folic acid, but many remain unaware of the benefits of available interventions to prevent HIV transmission and birth defects. Although it appears that some women reduce their risk for adverse pregnancy outcomes after learning of their pregnancy, the data suggest that a substantial proportion of women do not. Furthermore, if such change occurs it is often too late to affect outcomes, such as birth defects resulting from alcohol consumption during the periconception period. Preconception interventions are recommended to achieve a more significant reduction in risk and further improvement in perinatal outcomes.

Full text

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Matern Child Health J (2006) 10:S101–S106
DOI 10.1007/s10995-006-0093-z
REPORT
Prevalence of Risk Factors for Adverse Pregnancy Outcomes
During Pregnancy and the Preconception
Period—United States, 2002–2004
John E. Anderson · Shahul Ebrahim · Louise Floyd ·
Hani Atrash
Published online: 19 May 2006
C ?Springer Science+Business Media, Inc. 2006
Abstract Objectives: To assess the prevalence of risk fac-
tors for adverse pregnancy outcome during the preconcep-
tion stage and during pregnancy, and to assess differences
between women in preconception and pregnancy. Methods:
Datafromthe2002and2004BehavioralRiskFactorSurveil-
lanceSystem,UnitedStates,wereusedtoestimatethepreva-
lenceofselectedriskfactorsamongwomen18–44inthepre-
conception period (women who wanted a baby in the next
12 months, and were not using contraception, not sterile and
not already pregnant) with women who reported that they
were pregnant at the time of interview. Results: Major health
risks were reported by substantial proportions of women in
the preconceptional period and were also reported by many
pregnant women, although pregnant women tended to report
lowerlevelsofriskthanpreconceptionwomen.Forexample,
54.5% of preconception women reported one or more of 3
riskfactors(frequentdrinking,currentsmoking,andabsence
of an HIV test), compared with 32.0% of pregnant women
(p < .05). The difference in the prevalence of these three risk
factorsbetweenpreconceptionandpregnancywassignificant
for women with health insurance (52.5% in preconception
vs. 29.4% in pregnancy, p < .05), but not for women without
insurance (63.4% vs. 52.7%, p > .05). Conclusions: Women
appear to be responding to messages regarding behaviors
that directly affect pregnancy such as smoking, alcohol con-
J. E. Anderson (?)
Division of Reproductive Health/K-22, Centers for Disease
Control and Prevention,
Atlanta, GA 30333
e-mail: jea1@cdc.gov
S. Ebrahim · L. Floyd · H. Atrash
Division of Birth Defects and Developmental Disabilities,
Centers for Disease Control and Prevention,
Atlanta, GA 30333
sumption and taking folic acid, but many remain unaware of
the benefits of available interventions to prevent HIV trans-
mission and birth defects. Although it appears that some
women reduce their risk for adverse pregnancy outcomes
after learning of their pregnancy, the data suggest that a sub-
stantial proportion of women do not. Furthermore, if such
change occurs it is often too late to affect outcomes, such
as birth defects resulting from alcohol consumption during
the periconception period. Preconception interventions are
recommended to achieve a more significant reduction in risk
and further improvement in perinatal outcomes.
Keywords Pregnancy.Riskfactors.Preconception
Introduction
Although the US has achieved substantial gains in improv-
ing the health of women and children, and infant mortality
has reached record low levels, the US presently ranks 27th
among established market economies in infant mortality [1].
Four recurring causes account for more than half of all in-
fant deaths: birth defects, disorders related to short gesta-
tion and preterm birth, maternal complications of pregnancy
(including complications of the placenta, cord and mem-
branes), and sudden infant death syndrome [2]. In recent
years some causes of infant mortality have increased, par-
ticularly in the percentage of births that were preterm and
of low birth weight [3]. In 2002, congenital anomalies, low
birthweight,pretermdelivery,andmaternalcomplicationsof
pregnancyaccountedfor14,263(50.9%)ofthe28,034infant
deaths [2].
Relativelylittleisknownabouttheriskfactorsunderlying
the continued increase in these adverse outcomes. Adequate
prenatal care has long been considered as an opportunity to
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S102 Matern Child Health J (2006) 10:S101–S106
reducesuchrisks.However,despiteincreasesinaccesstoand
utilization of early prenatal care, interventions and efforts
directed at addressing such risk factors fall short of their
goal. Indeed, the effects of such efforts may have reached
their peak, and new approaches may be necessary. Reviews
on selected risk factors indicate that a large proportion of
women enter pregnancy with pre-existing risks for adverse
pregnancy outcomes. Although some women tend to take
action to reduce their risk as soon as they learn that they
are pregnant, the extent of pregnancy related change in risk
factors varies considerably and often does not occur early
in pregnancy when teratogenic effects are more pronounced.
Moreover, post-pregnancy relapse is high [4]. For example
in the period 1996–1998 the reported reduction in the use
of alcohol, tobacco and illicit drugs in the first trimester
was 46, 28, and 28% respectively [4]. Such information is
importanttotheemergingemphasisonpreconceptioncareas
acomplementaryapproachtoreduceriskstopregnancy.This
paper provides nationally-representative estimates on risks
during the preconception period and describes the apparent
reductions in risk achieved during pregnancy for all known
risk factors for which data are available.
Data
The estimates presented herein are based on data from
the 2004 Behavioral Risk Factor Surveillance System
(BRFSS) [5]. However, because not all risk indicators that
were considered were included in the 2004 BRFSS, 2002
data were used for a small number of risk indicators for
which the 2002 BRFSS provided the most recently available
data. The BRFSS is an ongoing annual telephone survey
of the non-institutionalized adult civilian population aged
18 years and older conducted in each state. The survey ob-
tains information on a wide range of modifiable risk be-
haviors. In 2004 the median response rate for the BRFSS
state surveys was 52.7 percent. This rate represents an esti-
mateofthepercentageofeligiblerespondentsthatcompleted
telephone interviews, and is computed based on procedures
recommended by the Council of American Survey Research
Organizations(http://www.casro.org/resprates.cfm.)Incom-
parison with other national surveys, BRFSS data appear to
be of good quality [5]. Additional technical information is
available online at http://www.cdc.gov/brfss/.
The survey includes core modules asked in all states, ro-
tating modules asked every second year in all states, and
optional modules that are included only in some states. Be-
ing a general survey, the BRFSS lacks information on some
factors of interest to the present topic, for example month of
pregnancy for pregnant women, or information on prenatal
care.Further,theBRFSSisnotdesignedspecificallytostudy
all known risk behaviors at preconception or pregnancy. In
addition, as an interview survey, the survey relies on self-
reported data which contain an unknown level of reporting
error.
Identification of women in the preconception group in the
BRFSSismadepossiblebyquestionsintroducedinthe“fam-
ilyplanningsection”ofthequestionnaire.Theavailabilityof
these questions makes it possible to compare risk behaviors
among women about to become pregnant with those who
are already pregnant on a large and nationally-representative
sample of women. Women in the preconception period were
identified as those who reported that they wanted a baby
in the next 12 months, were not using contraception, were
not sterile and were not already pregnant. Women who were
pregnant were identified based on the response to the ques-
tion “To your knowledge are you now pregnant?” Age of
gestation was not assessed in this survey. Data were aggre-
gated across states to make national estimates. For 2004 this
resulted in a total national U.S. sample of 70,917 women
aged 18 to 44 years, of whom 2308 (3.4%) were classified
into the preconception period, and 2998 (4.7%) reported that
they were pregnant at the time of their interview. The corre-
sponding number of women in the 2002 are 61,284 women
18–44, with 2204 (3.7%) in the preconception period, and
2556 (4.6%) pregnant women. The analysis on folic acid
and vitamins are based on surveys in 12 states in 2004. The
results for these items are generalizable to the populations
of these 12 states (shown in Table 2) but not to the entire
United States population.
Statistical methods
The percentage of women exposed to 21 risk indicators was
identified for women in 2 groups: women in the preconcep-
tionperiod,andpregnantwomen(Table1).Thecategoriesof
riskindicators for which data are available include perceived
generalandmentalhealth,lackofmedicalinsurance,knowl-
edge of HIV prevention and practices, alcohol and tobacco
use, obesity, nutrition including folic acid uptake for the pre-
vention of birth defects, and presence of chronic medical
conditions.
Becausethesearenotlongitudinaldataitwasnotpossible
to observe behavior change in individual women. Rather the
prevalenceofriskfactorswascomparedbetweenpreconcep-
tion and pregnant women as a proxy measure of pregnancy-
related risk reduction [6], although is is possible that other
factors could influence the differences between preconcep-
tion and pregnant women. The statistical significance be-
tween preconception and pregnant women of the percentage
reporting each risk factor, was assessed using a t-test. All
statistical analysis was based on weighting factors designed
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Matern Child Health J (2006) 10:S101–S106S103
Table 1
(Vital Statistics data)
Comparison of age and race/ethnicity, 2004 Women in preconception and pregnant (BRFSS) and Births
BRFSS
Preconception women
Percent
Pregnant women
Percent
Vital statistics
births Percent
+/− CI
+/− CI
Age group
18–19
20–24
25–29
30–34
35–39
40–44
2.0
16.3
23.4
28.4
18.5
11.4
100.0
0.9
3.3
3.1
3.1
2.5
2.2
7.5
26.5
26.5
26.2
10.2
3.1
100.0
2.2
3.0
2.7
2.8
1.5
0.9
7.1
26.1
27.9
24.4
12.0
2.6
Race/ethnicity
NH White
NH Black
Hispanic
Others
64.9
11.9
16.0
7.2
100.0
3.9
2.5
3.5
2.1
60.1
11.5
23.0
5.5
100.0
3.4
1.9
3.4
1.6
56.8
13.6
22.5
7.2
100.0
Note. For BRFSS estimates, 95% confidence interval = Percent +/− CI. Vital statistics data: Hamilton BE, Martin
JA, Ventura SJ, Sutton PD, Menacker F. Births: Preliminary data for 2004. National vital statistics reports; vol 54 no
8. Hyattsville, Maryland: National Center for Health Statistics. 2005.
to produce unbiased estimates, and statistical tests were ad-
justed for complex sample design using the software for sur-
vey data analysis (SUDAAN, Research Triangle Institute,
Research Triangle Park, NC).
Results
Comparisons with vital statistics data on births in 2004 indi-
cate that the 2004 BRFSS respondents in the preconception
stage and pregnant when interviewed were distributed very
similarly by age and race-ethnicity to women giving birth
in 2004 (Table 1). Overall, for many risk factors, pregnant
womenreportedlowerprevalence ofriskthanpreconception
women (Table 2). Percentages reporting alcohol consump-
tionandsmokingweremuchlowerforpregnantwomenthan
preconception women. For example, 53.9% of preconcep-
tion women reported any use of alcohol in the past month,
compared with 10.7% of pregnant women, 19.4% of precon-
ception women reported current smoking in contrast to 8.4%
of pregnant women, and, in the 12 states that included the
question,44.8%ofpreconceptionwomenreportednottaking
vitamins with folic acid versus 19.9% of pregnant women.
For some risk indicators, no statistically significant dif-
ference was observed between women in the preconcep-
tion period and pregnant women. The lack of awareness
about methods to prevent mother-to-child HIV transmission
(PMTCT)wasnotsignificantlydifferentbetweenpreconcep-
tion women and pregnant women (38.2% vs. 34.1%). How-
ever, a small but significantly higher percentage of pregnant
womenreportedHIVrisk(6.9%)comparedtopreconception
women (4.3%), which is perhaps related to sexual risk be-
haviors being causally linked to both HIV and to unplanned
pregnancies.
Of concern, is that although a lower percentage of preg-
nantwomencomparedwithpreconceptionwomenhadnever
been tested for HIV, about one-fourth of pregnant women re-
mained untested, despite national recommendations that call
for all pregnant women to be tested for HIV [7].
In the case of chronic diseases such as diabetes, the lower
level of disease among pregnant women may indicate self-
selection of diabetic women to avoid pregnancy. Of note,
nearly one fifth of the women in preconception period were
obese(definedashavingabodymassindexorBMIofgreater
than 30) and twice that number were overweight (BMI of
greater than 25) (Table 2). Most preconception and pregnant
women did not report consuming the recommended 5 serv-
ings of fruits and vegetables per day [8], although the per-
centage was lower for pregnant women (64.7%) compared
with women in the preconception period (74.9%). Indicators
of general well being and recent dental care were not differ-
ent between women in preconception period and pregnancy.
A composite measure of 3 basic pregnancy risks was
formed, frequent alcohol consumption, current smoking and
lack of an HIV test, in order to use the BRFSS data to illus-
tratethesizeofthetargetpopulationsforpreconceptioncare.
These are risk factors for which we have data that are gen-
eralizable to the US population, and for which interventions
or information are widely available or promoted. The results
indicate that 54.5% of preconception women reported one or
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S104 Matern Child Health J (2006) 10:S101–S106
Table 2
Health risk indicators by pregnancy status Women 18–44, 2004 and 2002 BRFSS
Preconception women
Percent
Pregnant women
Percent
+/− CI
+/− CI
2004 data–nationwidea
General Health
Poor/fair general health status
14+ days in past month mental health not good∗
No health plan∗
No dental visit past year
Told had diabetes∗
HIV
Don’t know about prevention of MTC HIV transmission
Never tested for HIV∗
1 or more HIV risk category∗
Alcohol/smoking
Any alcohol in past month∗
Average 1 or more drink per day, past month∗
Binging: Any occasions of 5+ drinks in past month∗
Frequent drinking: binging or 1 or more drinks per day∗
Current smoker∗
Obesity
Overweight, body mass index (BMI) >25
Obese, BMI >30
2004 data, 12 states onlyb,c
Folic acid
Don’t know about folic acid for birth defects prevention
Don’t take vitamins of any kind∗
Don’t take folic acid or multivitamin∗
Don’t take folic acid or multivitamin daily∗
Nutrition (2002 BRFSS)d
Fewer than 5 servings/fruit and vegetables∗
Fewer than 1 servings/fruit and vegetables
8.3
12.8
18.8
28.3
2.0
2.1
2.4
3.5
3.2
0.9
6.4
9.6
11.9
30.2
0.7
1.7
1.9
2.3
3.1
0.4
38.2
34.9
4.3
3.5
3.4
1.4
34.1
24.4
6.9
3.0
3.0
1.8
53.9
6.0
10.7
12.9
19.4
3.7
2.0
2.1
2.5
2.7
10.7
0.8
1.9
2.2
8.4
1.8
0.5
0.9
0.9
1.5
46.0
22.4
3.6
3.1
NA
NA
46.1
36.9
38.4
44.8
6.9
7.1
7.0
6.9
38.4
10.2
17.5
19.9
5.6
3.6
4.5
4.7
74.9
3.3
3.1
1.1
64.7
2.9
3.5
1.3
Note. 95% confidence interval = Percent +/− CI.
aUnweighted number of observations: Preconception women (2308), Pregnant Women (2998).
bUnweighted number of observations: Preconception women (607), Pregnant Women (756).
cStates: AZ, CO, FL, KY, MN, MT, NC, ND, NE, TX, VA, WI.
dUnweighted number of observations: Preconception women (2204), Pregnant Women (2556).
∗p < .05, preconception vs. pregnant women.
∗∗HIV risk: Any statement is true: in past year illegal drug injection, treated for STD, exchange for money/drugs,
uprotected anal intercourse.
Table 3
women aged 18–44 Women 18–44, 2004 BRFSS
Percentage and estimated number reporting any of 3 risks for pregnancy outcomeafor preconception and pregnant
Preconception women (Estimated number)
Percent
+/− CI
54.5∗
3.7 1,024
63.4 11.7
52.5∗
3.7
64.1∗
9.0
51.6∗
3.9
Currently pregnant women (Estimated number)
Percent +/− CI
32.03.1835
52.710.3 156
29.4 3.2679
46.3 9.2234
28.62.9 601
1000s
+/− CI
94
52
79
59
73
N 1000s
+/− CI
101
50
88
73
71
N
Total
No health plan/insurance
Others
No personal doctor
Others
2286
328
1957
448
1837
2949
303
2646
467
2482
222
802
278
745
Note. 95% confidence interval = Percent +/− CI and Estimated number +/− CI. Estimated number is the estimated number
of women in the category with one of the risk factors.
aAny of 3 risk factors: frequent drinking, current smoker, no HIV test.
∗difference between preconception and pregnant women significant, p < .05.
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Matern Child Health J (2006) 10:S101–S106S105
more of these 3 risk factors, which represents approximately
1 million preconception women (Table 3); 32.0 percent of
pregnant women had one or more of these risks, which is
equivalent to 835,000 pregnant women. Table 3 also shows
this composite risk factor by 2 measures of access to health
care, whether the woman had a health plan or insurance and
whethershehadapersonalphysician.Pregnantwomenhada
lowerpercentatriskinallcategoriesexceptforthosewithout
health insurance. Among women without insurance, the per-
centage reporting risk was not significantly lower for preg-
nant women, compared with preconception women. This
suggests that women with poorer access to health care, as
indicated by no health insurance, are not as likely as others
to adopt healthier behaviors when they become pregnant.
Discussion
The2004BRFSSprovidesanopportunitytomeasuretheex-
tent of risk behaviors on a relatively large sample of women
who are planning to become pregnant. These nationally-
representative survey data indicate that major health risks
were reported by substantial proportions of US women in
the preconception period. The data suggest that among those
at risk during preconception, the majority continued the risk
into pregnancy. Women appear to respond to messages re-
garding behaviors that can improve pregnancy outcomes
such as consuming of folic acid, and the reduction in smok-
ing, alcohol consumption, but many remain unaware of the
benefits of available interventions to prevent HIV transmis-
sion and birth defects. The fact that more than one-third
of preconception and pregnant women were not aware of
methods to prevent mother-to-child HIV transmission and
did not know about the benefits of taking folic acid dur-
ing pregnancy suggests that education and public infor-
mation programs could have some effect in reducing risk
behaviors.
Risk reduction appears to be lower among women who
have no health insurance. Other data are not available for
comparison of the overall burden of risk for adverse preg-
nancy outcomes among women in the preconception period
orpregnancy.However,dataonselectedindicatorspresented
here for pregnant women are comparable to the reported
range from other studies [4, 6, 8–11].
The finding that the percentage who report some risk be-
haviors is significantly lower among pregnant women com-
pared with women in the preconception period may indicate
thedesireofmanypregnantwomentoadopthealthierbehav-
iorstoachievethebestpossibleoutcomefortheirpregnancy.
Examination of three well known risk factors for which in-
terventionsareavailable(frequentalcoholconsumption,cur-
rentsmoking,orneverhavingbeentestedforHIV)illustrates
that risks for adverse pregnancy outcomes exist among more
than half of women in the preconception period and among
one-third of pregnant women. Nationwide, this represents
approximately one million women in the preconception pe-
riod and 835,000 pregnant women.
The data from the BRFSS are subject to potential errors
associated with survey research such as exclusion from the
sampling frame, non-response and reporting errors. BRFSS
is a telephone-based survey and might not be representative
ofthesmallpercentageofthepopulationwithouttelephones.
The BRFSS methodology contains steps to ensure accurate
estimation, including the use of weighting factors to com-
pensate for non-response rates. In addition, estimates from
BRFSS data have been found to be consistent with data from
other surveys [5]. The preconception and pregnant women
identified were distributed very similarly to women giving
birth in 2004 by age group and race/ethnicity, providing sup-
port for the representativeness of the data. In this report, the
reported risk behavior of women in the preconception stage
and pregnant women have been compared as a proxy for
the type of behavior change occurring between preconcep-
tion and pregnancy, but other factors could affect the actual
change in behavior among individual women.
For known risk factors, progress in efforts to reduce such
risksamongpregnantwomenhasbeenslow.Forexample,as
indicated in data collected on earlier rounds of the BRFSS,
alcohol consumption among pregnant women has remained
relativelysteadyoverthepastdecade[10].Evenamongthose
who reduce consumption of alcohol, tobacco, or drugs, post
pregnancy relapse of such behaviors have been found to be
veryhigh[4].Ofthe17maternalandinfanthealthobjectives
included in the Healthy people 2010 objectives, progress
has been made toward the target in 8 objectives [12]. Little
positiveprogresshasoccurredintheareasofmaternaldeath,
fetal alcohol syndrome, and low birth weight.
To close the gap in reduction of poor maternal and child
health outcomes, current maternal and child health initia-
tives should be complemented with alternate approaches,
including more emphasis on preconception health promo-
tion strategies among women of childbearing age. Recent
experience in the prevention of alcohol-exposed pregnancy
and prevention of neural tube defects through folic acid sup-
plementation has shown that such efforts are useful. In 2003,
the Project CHOICES Research Group reported the find-
ings of a feasibility study designed to provide prevention
counseling to women at high risk for an alcohol–exposed
pregnancy [13]. Brief interventions were found to be effec-
tive in reducing hazardous alcohol use in adults in a number
of well-controlled studies. Interventions generally consist
of advice, feedback, goal setting, and follow-up for further
assistance and support [14]. The use of a counseling style
referred to as “motivational interviewing” has also proven to
be effective in reducing problem drinking [15]. Results of
the initial follow-up assessment, suggest that this approach
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