Oxidative stress early in pregnancy and pregnancy outcome

Article (PDF Available)inFree Radical Research 42(10):841-8 · November 2008with61 Reads
DOI: 10.1080/10715760802510069 · Source: PubMed
Abstract
The objectives of this study were to determine whether oxidative stress early in pregnancy influenced pregnancy outcome. A combination of assays were used for exogenous and endogenous anti-oxidants together with two well accepted biomarkers for oxidative stress, the urinary excretion of 8-iso-PGF(2alpha) (a biomarker marker for lipid oxidation, n=508) and 8-oxo-7,8 dihydro-2 deoxyguanosine (8-OHdG, a biomarker for DNA oxidation, n=487). The two biomarkers tracked different pregnancy outcomes. Isoprostanes were associated with an increased risk of pre-eclampsia and a decreased proportion of female births. In contrast, 8-OHdG tracked lower infant birthweight and shortened gestation duration. Birth defects were associated with low levels of 8-OHdG.
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Oxidative stress early in pregnancy and pregnancy
outcome
T. Peter Stein, Theresa O. Scholl, Margaret D. Schluter, Maria J. Leskiw,
Xinhua Chen, Bernd W. Spur & Ana Rodriguez
To cite this article: T. Peter Stein, Theresa O. Scholl, Margaret D. Schluter, Maria J. Leskiw,
Xinhua Chen, Bernd W. Spur & Ana Rodriguez (2008) Oxidative stress early in pregnancy and
pregnancy outcome, Free Radical Research, 42:10, 841-848, DOI: 10.1080/10715760802510069
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Oxidative stress early in pregnancy and pregnancy outcome
T. PETER STEIN
1
, THERESA O. SCHOLL
2
, MARGARET D. SCHLUTER
1
,
MARIA J. LESKIW
1
, XINHUA CHEN
2
, BERND W. SPUR
3
, & ANA RODRIGUEZ
3
1
Department of Surgery,
2
Department of Obstetrics and Gynecology, and
3
Department of Cell Biology, University of Medicine
and Dentistry of New JerseySOM, 2 Medical Center drive, Stratford, NJ 08084, USA
Accepted by Professor F. Kelly
(Received 7 July 2008; revised 26 September 2008)
Abstract
The objectives of this study were to determine whether oxidative stress early in pregnancy influenced pregnancy outcome. A
combination of assays were used for exogenous and endogenous anti-oxidants together with two well accepted biomarkers
for oxidative stress, the urinary excretion of 8-iso-PGF
2a
(a biomarker marker for lipid oxidation, n508) and 8-oxo-7,8
dihydro-2 deoxyguanosine (8-OHdG, a biomarker for DNA oxidation, n487). The two biomarkers tracked different
pregnancy outcomes. Isoprostanes were associated with an increased risk of pre-eclampsia and a decreased proportion of
female births. In contrast, 8-OHdG tracked lower infant birthweight and shortened gestation duration. Birth defects were
associated with low levels of 8-OHdG.
Keywords: Oxidative stress, pregnancy, 8-hydroxy-2-deoxyguanosine, isoprostane, SOD, GPx, dietary antioxidants
Introduction
Oxidative stress results from an imbalance between
the production of reactive oxygen species (ROS),
anti-oxidants and repair processes. Proteins, lipids
and DNA are all vulnerable to oxidative damage
which has been implicated in the aetiology of a wide
variety of chronic diseases and acute pathological
states. Anti-oxidants defenses can be of either an
endogenous (e.g. Glutathione peroxidase (GPx),
Superoxide dismutase (SOD)) or exogenous nature
(e.g. the anti-oxidant vitamins [1,2]). Pro-oxidants
include smoking, iron and numerous environmental
agents.
Many studies, particularly animal models, have
documented the influence of maternal oxidative
stress on pregnancy outcome. Increased oxidative
stress in human pregnancy has been associated with
pre-eclampsia [36], hypertension and childhood
insulin resistance [7,8]. Because biomarkers usually
are measured late in pregnancy, it has been difficult to
separate the antecedents of oxidative stress from
consequences. There is little data on the influence
of maternal oxidative stress early in pregnancy when
antioxidant activity of the conceptus is minimal and
embryonic and foetal susceptibility likely to be
maximized [9,10].
The objectives of this study were to determine
whether oxidative stress early in pregnancy influenced
pregnancy outcome in a cohort of urban, low income
and minority pregnant women. We used a combina-
tion of assays for exogenous and endogenous anti-
oxidants together with two well accepted biomarkers
for oxidative stress. These are the urinary excretion of
8-iso-PGF
2a
(isoprostane) and 8-oxo-7,8 dihydro-2-
deoxyguanosine (8-OHdG). 8-OHdG is a marker for
oxidative damage to DNA [11,12] and isoprostane a
marker for the oxidative damage of lipids [13,14]
Correspondence: T. P. Stein, Department of Surgery, University of Medicine and Dentistry of New JerseySOM, Science Center, 2 Medical
Center Drive, Stratford, NJ 08084, USA. Tel: 856-795-0192. Email: tpstein@umdnj.edu
ISSN 1071-5762 print/ISSN 1029-2470 online # 2008 Informa UK Ltd.
DOI: 10.1080/10715760802510069
Free Radical Research, October 2008; 42(10): 841848
Downloaded by [Rowan University] at 10:09 20 April 2016
generated by the auto-oxidation of arachidonic acid
[15].
Materials and methods
The samples used for this study were obtained from a
prospective study on the effects of maternal nutrition
and growth in generally healthy pregnant women
from Camden, NJ. Camden is one of the poorest
cities in the US. Participants include young (518
years) and more mature (1945 years) women enrol-
ling for prenatal care in Camden clinics. Gravidas
with serious non-obstetric problems (6e.g. lupus,
diabetes mellitus Type 1 or Type 2 and seizure
disorders, malignancies, drug or alcohol abuse)
were excluded. Approximately 80% of gravidae who
were eligible agreed to participate. We focused on
samples and data from 989 gravidas enrolling in the
study between January 1998 and April 2005. The
Institutional Review Board of the University of
Medicine and Dentistry of New Jersey (Stratford,
NJ) approved the study.
Socioeconomic, demographic, lifestyle and dietary
data were obtained by interview at entry to prenatal
care (12.190.1 weeks (mean, standard error) for
women entering by week 16, the group of interest in
this report). Urine and blood specimens were
collected at entry to care, the blood was centrifuged
and aliquots of the serum and plasma stored
at 708C until analysed. Metaphosphoric acid
(0.5 ml of 10% metaphosphoric acid) was added to
a 0.5 ml aliquot of plasma for vitamin C analysis.
Dietary information was obtained by recall of the
previous days’ intake for the entry to care visit and for
two additional visits (weeks20 and28 gestation).
The resultant data was processed with databases from
the Campbell Institute of Research and Technology
(Campbell Soup Company) in Camden, NJ, and the
resultant nutrient values averaged across the preg-
nancy.
Pregravid weight was determined by recall. BMI
was computed as pregravid weight (in kg) divided by
height
2
(m). Information on current and past
pregnancy outcomes, complications and infant ab-
normalities, infant birth weight and birth defects were
abstracted from the prenatal record, the delivery
record, delivery logbooks and the infant’s chart.
Gestation duration was based upon the gravidas’
last normal menstrual period (LMP) confirmed or
modified by ultrasound. Preterm delivery was defined
by a delivery occurring at less than 37 completed
weeks gestation. Small-for-gestational age (SGA) was
defined by a birth weight for gestation below the 10
th
percentile of a standard which adjusts for maternal
ethnicity, parity and foetal sex [16].
The diagnosis of pre-eclampsia was based upon
high maternal blood pressure (systolic blood pressure
]140 mm Hg systolic or diastolic blood pressure
] 90 mm Hg) and proteinuria (]1 by dipstick)
after week 20 in a previously normotensive woman
[4]. Data on infant birth weight, birth defects and
all other measures related to the outcome of the
pregnancy were abstracted from patient records.
Commercially available kits were used to measure
erythrocyte concentrations of glutathione peroxidase
(GPx, Oxford Biomedical research, Oxford, MI) and
superoxide dismutase (SOD, Oxis Research, Foster
City, CA). Plasma ferritin, serum iron and unsatu-
rated iron binding capacity (UIBC) were determined
with kits obtained from Bio-Rad (Hercules, CA).
Total iron binding capacity was calculated from the
sum of serum iron and UIBC. Plasma vitamin C was
assayed colourimetrically [17] and vitamin E
a
and E
g
by HPLC [18]. Cholesterol was determined by the
Lieberman-Burchardt method using a kit marketed
by Pointe Scientific (Canton, MI). Inter and intra
coefficients of variation were as follows: SOD 6.3 and
3.5%, GPx 5.9 and 3.1%, ferritin 5.0 and 2.6%,
serum iron 5.0 and 2.6%, unsaturated iron binding
capacity 3.0 and 2.6%, Vitamin E
a
1.0 and 8%,
vitamin E
g
0.8 and 8%, vitamin C 7.8 and 5.2% and
cholesterol 2.0 and 2.7%. Data on circulating levels
of vitamin E
a
and vitamin E
g
were adjusted for
cholesterol.
8-OHdG in the urine was analysed by isotope
dilution gas chromatography-mass spectrometry
(gc-ms) with selective ion monitoring (SIM
[1921];
18
O labelled 8-OHdG was used as the
internal standard [19]). 8-[
18
O] hydroxyl-2’-deoxy-
guanosine was prepared by using a modification of
the method of Hermanns et al. [22] by brominating
2’-Deoxyguanosine (Aldrich, Milwaukee, WI) with
N-Bromosuccinimide in Acetonitrile/Water (4:1)
followed by hydrolysis with H
2
18
O (99%, Cambridge
Isotopes, Cambridge, MA) [23]. The purity
was99% as determined by HPLC/UV analysis
and the isotopic purity as determined by MS analysis
was93%.
Similarly the urinary 8-iso-PGF
2a
isoprostane
concentration was measured by GCMS with isotope
dilution and selective ion monitoring.
2
H 8-iso-
PGF
2a
was used as the internal standard (Cayman
Chemicals, Ann Arbor, MI). Partially resolved peaks
( 10%) were resolved using the Peakfit deconvolu-
tion software program (Systat Inc., Chicago, IL).
Isoprostane and 8-OHdG values were normalized to
creatinine. Inter and intra coefficients of variation
were 5.2 and 13.4% for isoprostane and 4.8 and
12.7% for 8-OHdG.
Data analyses
The significance of the association of 8-OHdG
and isoprostane with maternal characteristics was
assessed using analysis of variance (ANOVA), Chi
842 T. P. Stein et al.
Downloaded by [Rowan University] at 10:09 20 April 2016
Square and t-test. The p for trend was computed and,
when appropriate, the highest and lowest quintiles of
8-OHdG or isoprostane were contrasted.
Potential confounding variables associated in
Camden with infant birth weight (age, parity, smok-
ing, ethnicity, pregravid BMI) were included in
multivariable models. Separate models were fitted
for birth weight, gestation duration, birth weight
adjusted for gestation and other outcomes of interest
(pre-eclampsia, preterm delivery, small for gestation
births). Separate models were fit as well for individual
pro-oxidants (serum ferritin, iron, TIBC, UIBC),
endogenous antioxidants (GPx, SOD) and circulat-
ing levels of exogenous anti-oxidants (vitamins E
a
,E
g
and C) by ANOVA, multiple logistic or multiple
linear regression, after control for potential
confounding variables. Confounding was assessed
by comparing crude and adjusted odds ratios or
regression coefficients. Adjusted odds ratios (AOR)
and their 95% confidence intervals (95% CI) were
computed from the logistic regression coefficients
and their corresponding covariance matrices. Data
were analysed with SAS version 9.0 (SAS Institute,
Cary, NC). Since both creatinine adjusted and
unadjusted data gave similar results, the adjusted
data are presented. Data are presented by quintile or
as the mean9standard error (SEM).
Although we aimed to obtain data early in preg-
nancy, actual gestation at entry ranged from 528
weeks (n989). After eliminating subjects who
miscarried, had a foetal demise or delivered their
pregnancy elsewhere, outcome data from 922
gravidae remained. To have at least 500 subjects for
the isoprostane analyses (100 per quintile) we cut at
16 weeks to give 508 cases with a mean entry to care
time of 12.190.1 weeks. For 8-OHdG the corre-
sponding numbers amounted to n487 because of a
contaminating peak in the mass spectrum which we
were unable to resolve. Comparison of outcomes data
sets from these subjects with the main cohort did not
reveal any differences or trends towards differences.
Results
Both 8-OHdG and 8-iso-PGF
2a
are markers for
oxidative stress, but in this study they did not
correlate with each other for either the total group
(r
2
0.002, p0.989) or the sub-set of women with
any poor pregnancy outcomes.
Maternal characteristics
Gravidae in the early entry cohort had a mean age of
23.390.2 years (mean9standard error, SEM)
and the majority were parous (61%) and non-
smokers (84.5%). Most were Hispanic (45.3%) or
African American (37.4%). Pregravid BMI averaged
26.490.3 kg/m
2
. Mean gestation duration was
38.690.1 completed weeks and the mean birth
weight 3199924 g.
Tables I and II show the relationships between the
creatinine adjusted 8-OHdG (Table I) and isoprostane
(Table II) and relevant maternal characteristics for the
early entry cohort. Data on both markers suggested
that smoking was associated with increased oxidative
stress. When mean levels of 8 OHdG were examined
Table I. Creatinine adjusted 8-OHdG quintile and maternal characteristics.
Quintile 1 2 3 4 5 p for trend
n 97 97 97 99 97
8-OHdG (ng/mg Creat) B17.6 17.622.6 22.629.9 29.938.9 38.9
Age (years) 24.090.5 22.490.5 23.390.5 23.590.5 23.390.5 0.931
Pre-gravid BMI (kg/m
2
) 27.290.7 27.690.7 27.290.7 26.490.7 24.090.7
a
0.001
Diet
Protein (g/d) 90.893.8 83.893.8 88.893.6 90.993.6 89.893.8 0.677
Energy (kcal/d) 2227974 2222974 2147971 2187970 2207975 0.759
Carbohydrate (g/d) 279910 293910 260910 268910 282910 0.584
Fat (g/d) 90.893.8 83.793.8 88.892.6 90.893.6 89.893.8 0.875
Vitamin C (mg/d) 154912 211921 144911 165920 164913 0.758
Vitamin E (mg/d) 8.891.0 6.990.3 6.790.3 6.890.3 7.490.4 0.110
Parous% 66 (68.0) 60 (61.9) 60 (61.9) 65 (65.7) 49 (50.5)
Nulliparous% 31 (32.0) 37 (38.1) 37 (38.1) 34 (34.3) 48 (49.5) 0.046
Cigarette smoking% 10 (10.4) 14 (14.4) 14 (14.4) 17 (17.2) 21 (21.7) 0.031
Ethnicity%
Hispanic 37 (38.1) 33 (34.0) 51 (52.6) 51 (51.5) 48 (49.5)
African American 54 (55.7) 49 (50.5) 29 (29.9) 27 (27.3) 23 (23.7)
White & other 6 (6.2) 15 (15.5) 17 (17.5) 21 (21.2) 26 (26.8) 0.777
Medicaid% 96 (99.0) 96 (99.0) 96 (99.0) 95 (96.0) 89 (91.8) 0.002
Data are unadjusted means9SE or proportions, trends computed by ANOVA or Mantel Haenszel Chi-Square.
a
vs quintile 1, p0.001.
Oxidative stress & pregnancy 843
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by maternal smoking status the difference remained
significant (38.893.5 ng/mg Creat for smokers vs
29.591.5 ng/mg Creat. for non-smokers, p0.016);
for isoprostane, levels approached significance
(18.692.1 ng/mg Creat for smokers, 15.090.9 mg/
ng creatinine non-smokers, p0.12).
A difference in the pattern of association was noted
for the biomarkers. For example, pre-gravid BMI was
significantly higher for gravidae in the highest quintile
of maternal urinary isoprostane excretion. The
opposite was found for 8-OHdG where higher excre-
tion was associated with significantly lower pre-gravid
BMI (Tables I and II). Low-income gravidae
(pregnancy care was financed by Medicaid) had lower
levels of 8-OHdG but higher levels of isoprostane
compared to Medicaid non-recipients. Parous
gravidae tended to have lower excretion of 8-OHdG
when compared to nulliparae, but similar excretion of
isoprostane. Other relationships are discussed in the
paragraphs that follow.
Blood pro-oxidants and anti-oxidants
Serum levels of UIBC and TIBC were significantly
decreased and serum ferritin levels significantly
increased with higher 8-OHdG excretion. In contrast
UIBC and TIBC tended to rise as levels of isopros-
tane fell, a trend which approached but did not attain
significance; serum ferritin was unrelated to isopros-
tane excretion (Tables III and IV).
Dietary intake of vitamins E and C was unrelated
to excretion of isoprostane and 8-OHdG (Tables I
and II). While higher plasma levels of vitamin E
g
were
associated with increased isoprostane, there was no
Table II. Creatinine adjusted isoprostane and maternal characteristics.
Quintile 1 2 3 4 5 p for trend
n 102 103 101 100 102
Isoprostane (ng/mg Creat) B4.49 4.497.49 7.5012.36 12.3721.39 21.39
Age (years) 23.790.5 23.290.5 23.490.5 22.190.5 24.290.5 0.100
Pre-gravid BMI (kg/m
2
) 26.190.7 25.690.6 26.590.7 26.390.7 28.190.7
a
0.021
Diet
Protein (g/d) 85.893.6 92.893.6 86.493.6 88.793.7 89.293.6 0.817
Energy (kcal/d) 2177971 2270970 2189971 2171971 2113970 0.316
Carbohydrate (g/d) 28599 28399 27699 26299.3 25999.3 0.015
Fat (g/d) 79.793.7 87.393.7 84.193.7 87.393.7 81.993.7 0.714
Vitamin C (mg/d) 169912 155911 185923 155914 151910 0.418
Vitamin E (mg/d) 7.290.6 8.390.7 7.090.3 7.090.3 6.790.4 0.133
Parous% 62 (60.8) 65 (63.1) 70 (69.3) 53 (53.0) 63 (61.8)
Nulliparous% 40 (39.2) 38 (36.9) 31 (30.7) 47 (47.0) 39 (38.2) 0.599
Cigarette smoking% 13 (12.8) 16 (15.5) 15 (15.0) 15 (15.0) 22 (21.6) 0.135
Ethnicity%
Hispanic 40 (39.2) 38 (36.9) 53 (52.5) 46 (46.0) 55 (53.9)
African American 44 (43.1) 45 (43.7) 33 (32.7) 42 (42.0) 25 (24.5)
White & other 18 (17.6) 20 (19.4) 15 (14.9) 12 (12.0) 22 (21.6) 0.100
Medicaid% 96 (94.1) 97 (94.2) 100 99.0) 99 (99.0) 101 (99.0) 0.006
Data are unadjusted means9SE or proportions, trends computed by ANOVA or Mantel Haenszel Chi-Square.
a
vs quintile 1, p0.030.
Table III. Adjusted OHdG by quintile and antioxidant/oxidant concentrations (mean9SE).
OHdG Quintile 1 2 3 4 5 p for trend
Serum Iron (mg/dl) 73.994.8 77.994.5 81.294.5 67.795.2 75.795.1 0.723
UIBC (mg/dl) 269.099.5 248.198.9 223.398.8 244.02910.3 232.2910.19
a
0.015
TIBC (mg/dl) 339.398.1 327.797.6 304.497.4 312.298.7 308.998.5
b
0.005
Ferritin (ng/ml) 33.594.8 45.394.7 52.294.7 53.494.6 56.294.9
c
0.001
GPX (mU/mg Hb) 26.390.7 23.790.7 24.390.7 24.890.7 25.290.8 0.594
SOD (mU/mg Hb) 2.6590.05 2.3390.05 2.3790.05 2.3190.05 2.3890.05
d
0.023
Vitamin C (ng/ml) 16.590.4 16.590.4 16.690.3 16.890.3 16.790.4 0.528
Vitamin E
a
(ng/ml) 10.390.3 10.690.3 10.090.3 10.190.3 10.290.3 0.313
Vitamin E
g
(ng/ml) 1.9190.07 1.9390.07 1.8390.07 1.8190.07 1.8990.07 0.497
Models were adjusted for age, BMI, smoking, ethnicity and parity. Vitamin E
g
and E
a
concentrations were also adjusted for serum
cholesterol.
a
vs quintile 1, p0.011;
b
vs quintile 1, p0.013;
c
vs quintile 1, p0.001;
d
vs quintile 1, p0.018.
844 T. P. Stein et al.
Downloaded by [Rowan University] at 10:09 20 April 2016
relationships between plasma levels of vitamins E
a
or
C and either isoprostane or 8-OHdG excretion
(Tables III and IV).
Both biomarkers showed similar associations with
SOD; activity was reduced in the highest quintile of
isoprostane or 8-OHdG compared to the lowest
quintile (Tables III and IV). GPX activity was reduced
for the highest quintile of isoprostane but was
unrelated to 8-OHdG excretion (Tables III and IV).
8-OHdG and outcome
Mean gestation duration and birth weight decreased
with increasing 8-OHdG (Tables V and VI). At
delivery there was a 208 g difference (p0.007)
in birth weight for women in the highest quintile of
8-OHdG at entry compared to women in the lowest
quintile. The difference was associated with
shortened gestation duration, which was 0.9 weeks
less for women in the highest quintile (Tables V and
VI). When infant birth weight was adjusted for
gestation duration as well as other potential
confounding variables included in previous models,
the difference was no longer significant (48 g birth
weight, comparing highest and lowest quintiles).
For the 19 babies diagnosed with (minor)
birth defects; the maternal 8-OHdG levels were
significantly lower than those of the controls (24.09
1.9 vs 29.190.7 ng/mg Creat, p0.046). Levels of
GPx also tended to be lower in these women (21.79
1.9 vs 25.290.7 m
M
/mg Creat, p0.033) and SOD
(2.2690.08 vs 2.3990.02 m
M
/mg Creat, p0.084).
Isoprostane 8-iso-PGF
2a
and outcome
Like 8-OHdG, high isoprostane excretion was
associated with poor pregnancy outcomes, but the
nature of the risk differed. While there was no
relationship between isoprostane and infant birth-
weight (Table VI), there was a significant trend for
risk of pre-eclampsia to increase with increasing
isoprostane (p0.029); pre-term delivery (p
0.085) tended to be increased as well (Table VI).
For pre-eclampsia, risk was nearly 5-times higher
when highest and lowest isoprostane quintiles were
compared and potential confounding variables were
controlled (AOR 4.96, 95% CI 1.54, 15.95). In
contrast, there was no relationships between
8-OHdG excretion and pre-eclampsia or pre-term
delivery (Table V).
There was a gender effect associated with isopros-
tane 8-iso-PGF
2a
. Elevated isoprostane excretion was
associated with an increased proportion of male
births (57% vs 40% for the highest and lowest
Table IV. Adjusted isoprostanes by quintile and antioxidant/oxidant concentrations (mean9SE).
Isoprostane Quintile 1 2 3 4 5 p for trend
Serum Iron (mg/dl) 70.995.1 75.894.7 83.495.1 78.194.5 71.294.8 0.788
UIBC (mg/dl) 238.1910.4 247.199.5 226.4910.3 239.699.1 263.799.7 0.185
TIBC (mg/dl) 308.598.8 320.398.1 306.998.7 319.997.7 335.598.3
a
0.053
Ferritin (ng/ml) 43.394.7 47.194.6 56.594.8 47.894.6 44.094.8 0.896
GPX (mU/mg Hb) 27.090.8 24.190.8 25.790.8 25.490.8 24.090.8
b
0.064
SOD (mU/mg Hb) 2.4790.05 2.4190.05 2.3790.05 2.3890.05 2.3390.05
c
0.044
Vitamin C (ng/ml) 16.790.4 17.190.3 16.490.4 16.690.4 16.390.4 0.295
Vitamin E
a
(ng/ml) 10.090.3 10.590.2 10.290.2 10.190.2 10.190.2 0.015
Vitamin E
g
(ng/ml) 1.9390.07 1.8490.07 1.8390.07 1.8590.07 1.9090.07 0.886
Models were adjusted for age, BMI, smoking, ethnicity and parity. Vitamin E
g
and E
a
concentrations were also adjusted for cholesterol.
a
vs quintile 1, p0.031;
b
vs quintile 1, p0.008;
c
vs quintile 1, p0.042.
Table V. Adjusted mean gestation duration, infant birthweight, proportion with SGA, preterm delivery and foetal gender for OHdG.
Quintile 1 2 3 4 5 p for trend
n 97 97 97 99 97
8-OHdG (ng/mg Creat) B17.6 17.622.6 22.629.9 29.938.9 38.9
Gestation duration (wks) 39.090.2 38.890.2 38.890.2 38.690.2 38.190.2
a
0.009
Birthweight (g) 3262958 3262958 3223956 3201956 3053959
b
0.014
SGA% 3 (3.2) 8 (8.7) 7 (7.3) 5 (5.1) 9 (9.9) 0.369
Pre-eclampsia% 10 (10.3) 9 (9.4) 8 (8.3) 5 (5.1) 5 (5.3) 0.217
Preterm delivery% 7 (7.3) 10 (10.8) 9 (9.4) 9 (9.1) 11 (11.8) 0.244
Gender%
Male 46 (47.9) 53 (57.0) 45 (46.9) 55 (55.6) 46 (49.5)
Female 50 (52.1) 40 (43.1) 51 (53.1) 44 (44.4) 47 (50.5) 0.659
All models were adjusted for maternal age, BMI, ethnicity, parity and cigarette smoking by multiple linear or logistic regression.
a
vs quintile 1, p0.014;
b
vs quintile 1, p0.007.
Oxidative stress & pregnancy 845
Downloaded by [Rowan University] at 10:09 20 April 2016
isoprostane quintiles, Tables V and VI). In contrast to
the situation with 8-OHdG, there was no association
between maternal isoprostane excretion and birth
defects.
Discussion
Early in pregnancy, urinary excretion of oxidative
stress markers probably reflects maternal rather than
foetal redox status. However what happens to the
mother is likely to happen to the foetus since foetal
anti-oxidant defenses are poor early in gestation
[9,10]. Numerous studies have shown that foetal
development and gestation duration are sensitive to
the maternal biochemical environment [24,25].
8-OHdG and isoprostane are uncorrelated markers
for different aspects of oxidative stress (DNA, lipids)
that track different routes whereby oxidative stress
impacts pregnancy outcome. This is not too surpris-
ing; oxidative stress can damage most biomolecules,
there is no reason for oxidative damage to a lipid
(measured by isoprostane) or to DNA (8-OHdG) to
lead to the same phenotypic outcome. Because the
origins of the two markers are known, our observations
provide information about routes whereby oxidative
stress has a potential impact on phenotypic expression.
8-OHdG
Low maternal adiposity, as measured by BMI, was
associated with a high level of oxidative stress as
measured by 8-OHdG excretion and a low level of
oxidative stress when measured by isoprostane excre-
tion. Other investigators have also found an inverse
relationship between BMI and urinary 8-OHdG
excretion in non-pregnant subjects [2628]. A number
of explanations have been proposed including a nutri-
tional deficiency, an artifact from the normalization of
the urinary data to creatinine and increased oxidative
metabolism in subjects with low BMI [2628].
Tables I and II shows that the subjects with high
8-OHdG were not nutritionally deficient. When we
examined the data without normalization to creati-
nine, the relationship between high urinary 8-OHdG
(in ng/ml) and lower birth weight remained (30629
65 g vs 3229955 g, pB0.05). Loft et al. [29]
suggested that the higher rate of 8-OHdG excretion
in lean subjects was due to a higher rate of oxidative
metabolism resulting in an increased availability of
reactive oxygen species. Overweight and obese
subjects tend to be less active than their leaner
counterparts [3032].
Elevated levels of maternal urinary 8-OHdG were
associated with reduced birth weight and shortened
gestation as well as with lower BMI (Tables V and
VI). Thus, it is plausible that increased 8-OHdG
excretion may be a factor underlying the consistent
but unexplained observation that an increased risk of
poor pregnancy outcome is associated with low
maternal BMI or weight [33]. In our study, the
highest quintile by 8-OHdG was associated with a
birth weight difference of more than 200 g and a 0.9
week reduction in gestation duration. Other studies
have found that women with high levels of urinary
8-OHdG measured closer to delivery had a predis-
position to low (B 2500 g) or lower infant birth
weight [34,35].
We suggest that chronically elevated oxidative
stress to maternal DNA may lead to increased risk
of altered gene expression. The perturbations will not
be permanent if normally operating DNA repair
mechanisms mend the damage. However, the cumu-
lative effect of numerous (minor) transient perturba-
tions of maternal gene expression could adversely
impact the maternal/foetal environment and lead to
shortened gestation [36].
Counter-intuitively, mothers of offspring with birth
defects (n19) had lower urinary 8-OHdG excretion
than the remainder of the cohort. This is the opposite
of what was expected from a simple model of
Table VI. Adjusted mean gestation duration, infant birthweight, proportion with SGA, preterm delivery and foetal gender for Isoprostane.
Quintile 1 2 3 4 5 p for trend
n 102 103 101 100 102
Isoprostane (ng/mg Creat) B4.49 4.497.49 7.5012.36 12.3721.39 21.39
Gestational duration (wks) 39.090.2 39.090.2 38.490.2 38.690.2 38.590.2 0.030
Birthweight (g) 3268.1955 3201954 3150955 3212955 3189956 0.403
SGA% 6 (6.1) 9 (8.8) 6 (6.1) 6 (6.3) 5 (5.1) 0.636
Pre-eclampsia% 5 (5.0) 7 (6.8) 4 (4.0) 4 (4.0) 15 (15.2)
a
0.029
Preterm delivery% 5 (5.1) 6 (5.9) 15 (15.3) 10 (10.1) 12 (12.0) 0.085
Gender%
Male 40 (40.4) 45 (44.1) 53 (54.1) 58 (58.6) 57 (57.0)
Female 59 (59.6) 57 (55.9) 45 (45.9) 41 (41.4) 43 (43.0) 0.007
All models were adjusted for maternal age, BMI, ethnicity, parity and cigarette smoking by multiple linear or logistic regression.
a vs quintile 1, Odds Ratio (OR)3.39 (95% Confidence Interval (CI) 1.18, 9.73); Adjusted Odds Ratio (AOR)4.96 (95% CI 1.54,
15.95).
846 T. P. Stein et al.
Downloaded by [Rowan University] at 10:09 20 April 2016
oxidative stress increasing DNA oxidation and lead-
ing to foetal damage. The incidence of birth defects is
related to increased oxidative stress, since maternal
GPx and SOD are lower in mothers of offspring with
birth defects, but levels of the marker for oxidative
stress, 8-OHdG, are decreased rather than increased.
Oxidative damage to DNA is repaired by the base
excision pathway; defects in this pathway have been
shown to increase DNA 8-OHdG content and
mutagenesis [37,38]. Thus the simplest explanation
is that there may have been a deficit in foetal ability to
repair damaged DNA. The products of oxidative
damage to the DNA remain in the DNA; they are not
‘repaired’ and fewer of the damaged nucleotides are
excreted in the urine. However, DNA repair mechan-
isms are heritable, so if the maternal repair mechan-
isms are compromised, the same processes are likely
compromised in the developing foetus. Unrepaired
damage to DNA can result in developmental dis-
orders; if genes are altered there may be ensuing
perturbations in metabolism leading to sub-optimal
intrauterine growth or gestation.
Isoprostane
The outcomes associated with high isoprostane
excretion were primarily maternal and secondarily
foetal. They relate to a serious complication of
pregnancy, pre-eclampsia, and to medically indicated
preterm delivery [4]. In contrast to 8-OHdG, in-
creased oxidative stress, as measured by higher
isoprostane excretion, was associated with a higher,
as opposed to a lower maternal BMI.
The F
2a
isoprostanes are derived from the free
radical oxidation of arachidonic acid, a polyunsatu-
rated fatty acid that is part of the adipose tissue store
[13,14]. Isoprostane excretion is positively related to
maternal adiposity [39] and to the adiposity measure
used in this study, higher BMI (Tables I and II), A
high BMI is a well-known risk factor for pre-
eclampsia [33]. Studies have demonstrated that
isoprostane levels are higher in women who subse-
quently develop pre-eclampsia [6,39,40]. As we have
demonstrated, this effect apparently is detectable
early in pregnancy.
Isoprostanes are potent vasoconstrictors [41,42].
The F
2a
isoprostanes constrict blood flow throughout
the body [42,43]. Vasoconstriction underlies pre-
eclampsia, thus providing a plausible link between
maternal oxidative stress, high BMI and the rise in
blood pressure that characterizes pre-eclampsia.
Therefore it seems reasonable that increased isopros-
tane excretion could underlie the well-know relation-
ship between high maternal BMI and serious
complications of pregnancy like pre-eclampsia [33].
In conclusion: (1) Both 8-OHdG and isoprostane
are biomarkers for oxidative stress early in pregnancy.
They are uncorrelated with each other, track different
aspects of oxidative stress and are related to different
levels of pregravid BMI. 8 OH-dG is related to lower
and isoprostane to higher maternal BMI. (2) Mater-
nal oxidative stress measured early in pregnancy
(12 weeks gestation on average) was associated with
pre-eclampsia, shortened gestation duration, lower
infant birth weight, the occurrence of minor con-
genital defects and a distortion in the sex ratio at birth
suggests that oxidative stress is antecedent to the
pathophysiology of adverse pregnancy outcomes
rather than a consequence of their occurrence. (3)
Thus, this research supports the prudence of paying
attention to maternal redox status early in pregnancy.
Acknowledgements
This work was supported by a grant from the
National Institute of Child Health and Human
Development, HD38329). We thank the staff of the
Osborn Family Health Center, Our Lady of Lourdes
Hospital for providing access to patients.
Declaration of interest: The authors report no
conflicts of interest. The authors alone are respon-
sible for the content and writing of the paper.
References
[1] Gitto E, Reiter RJ, Karbownik M, Tan DX, Gitto P, Barberi
S, Barberi I. Causes of oxidative stress in the pre- and
perinatal period. Biol Neonate 2002;81:146157.
[2] Halliwell B. Antioxidants and human disease: a general
introduction. Nutr Rev 1997;55:S44S52.
[3] Roberts JM, Hubel CA. Oxidative stress in preeclampsia. Am
J Obstr Gynecol 2004;190:11771178.
[4] Roberts JM, Pearson GD, Cutler JA, Lindheimer MD.
Summary of the NHLBI Working Group on Research on
Hypertension During Pregnancy. Hypertension Pregnancy
2003;22:109127.
[5] Williams MA, Woelk GB, King IB, Jenkins L, Mahomed K.
Plasma carotenoids, retinol, tocopherols, and lipoproteins in
preeclamptic and normotensive pregnant Zimbabwean wo-
men. Am J Hypertension 2003;16:665672.
[6] Scholl TO, Leskiw MJ, Chen X, Sims MR, Stein TP.
Oxidative stress, diet, and the etiology of preeclampsia. Am
J Clin Nutr 2005;81:13901396.
[7] Facchini FS, Hua N, Abbasi F, Reaven GM. Insulin
resistance as a predictor of age-related diseases. J Clin Endo
Metab 2001;86:35743578.
[8] Hofman PL, Regan F, Jackson WE, Jefferies C, Knight DB,
Robinson EM, Cutfield WS. Premature birth and later insulin
resistance. New Engl J Med 2004;351:21792186.
[9] Frank L, Groseclose EE. Preparation for birth into an O
2
-rich
environment: the antioxidant enzymes in the developing
rabbit lung. Pediatr Res 1984;18:240244.
[10] de Haan JB, Tymms MJ, Cristiano F, Kola I. Expression of
copper/zinc superoxide dismutase and glutathione peroxidase
in organs of developing mouse embryos, fetuses, and neo-
nates. Pediatr Res 1994;35:188196.
[11] Angerer J, Ewers U, Wilhelm M. Human biomonitoring: state
of the art. Int J Hyg Environ Health 2007;210:201228.
Oxidative stress & pregnancy 847
Downloaded by [Rowan University] at 10:09 20 April 2016
[12] Poulsen HE. Oxidative DNA modifications. Exp Toxicol
Pathol 2005;57(Suppl 1):161169.
[13] Kadiiska MB, Gladen BC, Baird DD, Germolec D, Graham
LB, Parker CE, Nyska A, Wachsman JT, Ames BN, Basu S,
Brot N, Fitzgerald GA, Floyd RA, George M, Heinecke JW,
Hatch GE, Hensley K, Lawson JA, Marnett LJ, Morrow JD,
Murray DM, Plastaras J, Roberts LJ 2
nd
, Rokach J, Shigenaga
MK, Sohal RS, Sun J, Tice RR, Van Thiel DH, Wellner D,
Walter PB, Tomer KB, Mason RP, Barrett JC. Biomarkers of
oxidative stress study II: are oxidation products of lipids,
proteins, and DNA markers of CCl
4
poisoning? Free Radic
Biol Med 2005;38:698710.
[14] Block G, Dietrich M, Norkus EP, Morrow JD, Hudes M,
Caan B, Packer L. Factors associated with oxidative stress in
human populations. Am J Epidemiol 2002;156:274285.
[15] Roberts LJ 2
nd
, Fessel JP, Davies SS. The biochemistry of the
isoprostane, neuroprostane, and isofuran pathways of lipid
peroxidation. Brain Pathol 2005;15:143148.
[16] Zhang J, Bowes WA, Jr. Birth-weight-for-gestational-age
patterns by race, sex, and parity in the United States
population. Obstet Gynecol 1995;86:200208.
[17] Jagota SK, Dani HM. A new colorimetric technique for the
estimation of vitamin C using Folin phenol reagent. Anal
Biochem 1982;127:178182.
[18] Bieri JG, Tolliver TJ, Catignani GL. Simultaneous determi-
nation of alpha-tocopherol and retinol in plasma or red cells
by high pressure liquid chromatography. Am J Clin Nutr
1979;32:21432149.
[19] Lin HS, Jenner AM, Ong CN, Huang SH, Whiteman M,
Halliwell B. A high-throughput and sensitive methodology for
the quantification of urinary 8-hydroxy-2?-deoxyguanosine:
measurement with gas chromatography-mass spectrometry
after single solid-phase extraction. Biochem J 2004;380:
541548.
[20] Schwedhelm E, Boger RH. Application of gas chromatogra-
phy-mass spectrometry for analysis of isoprostanes: their role
in cardiovascular disease. Clin Chem Lab Med 2003;41:
15521561.
[21] Il’yasova D, Morrow JD, Ivanova A, Wagenknecht LE.
Epidemiological marker for oxidant status: comparison of
the ELISA and the gas chromatography/mass spectrometry
assay for urine 2,3-dinor-5,6-dihydro-15-F2t-isoprostane.
Ann Epidemiol 2004;14:793797.
[22] Hermanns RCA, Zomer G, Jacqemijns M, Stavenuiter JG,
Westa AJR, Van de Werken G. Synthesis of 8-[
18
O] hydroxyl-
2?-deoxyguanosine. J Labelled Compounds 1994;34:
191197.
[23] Gannett PM, Sura TP. An improved synthesis of 8-Bromo-2-
deoxyguanosine. Syn Comm 1993;23:16111615.
[24] McCarthy C, Cotter FE, McElwaine S, Twomey A, Mooney
EE, Ryan F, Vaughan J. Altered gene expression patterns in
intrauterine growth restriction: potential role of hypoxia. Am J
Obst Gynecol 2007;196:e7176.
[25] Smith GC, Shah I, White IR, Pell JP, Crossley JA, Dobbie R.
Maternal and biochemical predictors of antepartum stillbirth
among nulliparous women in relation to gestational age of
fetal death. BJOG: Int J Obstet Gynaecol 2007;114:705714.
[26] Mizoue T, Tokunaga S, Kasai H, Kawai K, Sato M, Kubo T.
Body mass index and oxidative DNA damage: a longitudinal
study. Cancer Sci 2007;98:12541258.
[27] Loft S, Vistisen K, Ewertz M, Tjonneland A, Overvad K,
Poulsen HE. Oxidative DNA damage estimated by 8-hydro-
xydeoxyguanosine excretion in humans: influence of smoking,
gender and body mass index. Carcinogenesis 1992;13:
22412247.
[28] Kasai H, Iwamoto-Tanaka N, Miyamoto T, Kawanami K,
Kawanami S, Kido R, Ikeda M. Life style and urinary 8-
hydroxydeoxyguanosine, a marker of oxidative dna damage:
effects of exercise, working conditions, meat intake, body
mass index, and smoking. Jap J Can Res 2001;92:915.
[29] Loft S, Astrup A, Buemann B, Poulsen HE. Oxidative DNA
damage correlates with oxygen consumption in humans.
Faseb J 1994;8:534537.
[30] Ekelund U, Aman J, Yngve A, Renman C, Westerterp K,
Sjostrom M. Physical activity but not energy expenditure is
reduced in obese adolescents: a case-control study.[see
comment]. Am J Clin Nutr 2002;76:935941.
[31] Lazzer S, Boirie Y, Bitar A, Montaurier C, Vernet J, Meyer M,
Vermorel M. Assessment of energy expenditure associated
with physical activities in free-living obese and nonobese
adolescents. Am J Clin Nutr 2003;78:471479.
[32] Yoshioka M, Ayabe M, Yahiro T, Higuchi H, Higaki Y, St-
Amand J, Miyazaki H, Yoshitake Y, Shindo M, Tanaka H.
Long-period accelerometer monitoring shows the role of
physical activity in overweight and obesity. Int J Obesity
2005;29:502508.
[33] Institute of Medicine. Nutrition during pregnancy. Washing-
ton, DC: National Academy Press; 1990.
[34] Kim YJ, Hong YC, Lee KH, Park HJ, Park EA, Moon HS,
Ha EH. Oxidative stress in pregnant women and birth weight
reduction. Repr Toxicol 2005;19:487492.
[35] Scholl TO, Stein TP. Oxidant damage to DNA and
pregnancy outcome. J Matern Fetal Med 2001;10:182185.
[36] Crider KS, Whitehead N, Buus RM. Genetic variation
associated with preterm birth: a HuGE review. Genet Med
2005;7:593604.
[37] Paz-Elizur T, Krupsky M, Blumenstein S, Elinger D,
Schechtman E, Livneh Z. DNA repair activity for oxidative
damage and risk of lung cancer. J Natl Cancer Inst 2003;95:
13121319.
[38] Bruner SD, Norman DP, Verdine GL. Structural basis for
recognition and repair of the endogenous mutagen 8-oxogua-
nine in DNA. Nature 2000;403:859866.
[39] Chappell LC, Seed PT, Kelly FJ, Briley A, Hunt BJ,
Charnock-Jones DS, Mallet A, Poston L. Vitamin C and E
supplementation in women at risk of preeclampsia is asso-
ciated with changes in indices of oxidative stress and placental
function. Am J Obstet Gynecol 2002;187:777784.
[40] Parra M, Rodrigo R, Barja P, Bosco C, Fernandez V, Munoz
G, Soto-Chacone E. Screening test for pre-eclampsia through
assessment of uteroplacental blood flow and biochemical
markers of oxidative stress and endothelial dysfunction. Am
J Obst Gyn 2005;193:14861491.
[41] Cracowski JL, Devillier P, Durand T, Stanke-Labesque F,
Bessard G. Vascular biology of the isoprostanes. J Vascular
Res 2001;38:93103.
[42] Hou X, Roberts LJ 2nd, Gobeil F Jr, Taber D, Kanai K,
Abran D, Brault S, Checchin D, Sennlaub F, Lachapelle P,
Varma D, Chemtob S. Isomer-specific contractile effects of a
series of synthetic f2-isoprostanes on retinal and cerebral
microvasculature. Free Radic Biol Med 2004;36:163172.
[43] Kromer BM, Tippins JR. Coronary artery constriction by the
isoprostane 8-epi prostaglandin F
2
alpha. Br J Pharm
1996;119:12761280.
848 T. P. Stein et al.
Downloaded by [Rowan University] at 10:09 20 April 2016
    • "Pregnancy itself is a state of higher oxidative stress levels; and 8-isoprostane may be a useful marker for the risk for pregnancy complications [69]. It has been reported that isoprostane levels were significantly increased in pregnant women in relation to healthy non-pregnant women and were higher during the second and third trimester of pregnancy [69,70]. Isoprostane levels in CHAMACOS pregnant women appear to be higher than reported by similar methods in pregnant women from Europe [71]. "
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