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1 I
st Department of Gynecological Oncology and Gynecology, Medical University in Lublin
2II
nd Department of Obstetrics and Pathological Pregnancy, Medical University in Lublin
Archives of Perinatal Medicine 17 4), 199-203, 2011 ORIGINAL PAPER
Placental growth factor (PLGF) with PAPP-A
and free beta hCG assessment in women
between 11
th
and 14
th
weeks of gestation A RTUR CZEKIERDOWSKI1, SYLWIA CZEKIERDOWSKA 1, A RKADIUSZ K RZYŻ ANOWSKI2,
J ANUSZ K RACZKOWSKI2, EWELINA R OGALA 1, A LDONA NOWICKA 1
Abstract
Preeclampsia (PE) remains one of the leading causes of maternal, fetal and neonatal mortality and morbidity
worldwide. Early identification of a subgroup of patients with an increased risk for PE became one of the most
important goals in perinatal medicine. Our objective was to examine the possible relationship of PLGF measure-
ments in late 1st trimester of pregnancy with selected maternal clinical features, maternal serum concentrations
of pregnancy-associated plasma protein-A (PAPP-A), free $-human chorionic gonadotropin ($-hCG) and variouslate pregnancy complications. The studied group included 113 pregnant women with singleton pregnancies bet-
ween 11 weeks+0 days and 13 weeks +6 days of gestation. Mean age of these women was 38.8 years (range: 16
to 42 years). Mean neonatal weight at delivery was 3367 g (median – 3460 g, min-max 150-5660 g). Median mater-
nal serum PLGF concentration was 32.38 pg/ml (interquartile range: 23.6-46.6 pg/ml, SD = 51.18 pg/mol, min-
max = 10.1-593.5 pg/ml). Median concentrations of PLGF decreased with the increase of gestational age. Normal
vaginal delivery occurred in 52 women in the studied group and there were 61 cesarean sections performed for
various indications. Mean body mass index (BMI) value of studied pregnant women was 24.3 ± 4.1 (min-max: 18.4-
38.2). Fetal crown-rump length (CRL) ranged from 45 mm to 83mm and measured nuchal translucency (NT)
values ranged from 1.01 to 3.1 mm (median – 1.91 mm). Multiple of the Medians (MoM’s) of free beta HCG and
PAPP-A were 0.73 (range: 0.51-1.07) and 3.08 (range: 1.81-4.94), respectively. A significant correlation between
maternal serum PLGF concentrations and fetal CRL in the late 1st trimester of gestation was found R = 0.19;
p = 0.04). No statistically significant correlations were found between maternal serum PLGF levels and other stu-
died parameters such as: maternal BMI, fetal NT, and calculated MoM’s of free beta HCG as well as PAPP-A inmaternal serum (all p ’s > 0.005). We conclude that serum placental growth factor measurements in the late 1
st
trimester may provide additional prognostic value in predicting various late pregnancy complications including
preeclampsia.
Key words: early pregnancy, placental growth factor (PLGF), PAPP-A, preeclampsia screening
Prediction of fetal and maternal risk is the main goal
of perinatal care. Despite numerous conducted studies,
hypertensive disorders in pregnancy and, in particular,
preeclampsia (PE) remain one of the leading causes of
maternal, fetal and neonatal mortality and morbidity worldwide [4, 8]. Since in many countries a late first-
trimester screening for fetal aneuploidy is now offered
in general population of healthy pregnant women, the
early identification of a subgroup of patients with an in-
creased risk for PE became one of the most important
goals in perinatal medicine [3, 11, 16 ]. The most impor-
tant disorders in preeclampsia and intrauterine growth
retardation are associated with placental malfunction
[17]. Abnormal trophoblast invasion late in the 1st tri-
mester, accompanied by the absence of appropriate ma-
ternal spiral artery modification with the resulting pla-
cental ischemia are all associated with the release of se-
veral specific molecules, mostly proteins, as well as cell-
free fetal DNA and RNA [13, 16, 17]. These molecules
can now be detected in the maternal blood, and changesin their concentrations can be further used for early
identification and prediction of preeclampsia, long before
to the appearance of the typical clinical symptoms of
hypertension with proteinuria [16, 17].
Currently, for women between 11th and 14
th week of
gestation several biophysical and biochemical markers
have been proposed, most frequently in a combinatory
analysis [14]. Some of early predictors or diagnostic
tools of preeclampsia include measurements of preg-
nancy associated protein A (PAPP-A), placental growth
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A. Czekierdowski, S. Czekierdowska, A. Krzy ż anowski et al.200
factor (PLGF), placental protein 13 (PP-13), vascular
endothelial growth factor (VEGF) and it’s receptors
(VEGF-R) [7, 10, 18, 19]. It has been also found that ab-
normal maternal uterine artery Doppler in association
with elevated maternal serum AFP, hCG, or inhibin-A or
decreased PAPP-A may effectively identify a group of wo-
men at greater risk of IUGR and gestational hyper-
tension with proteinuria. Uterine artery Doppler measu-
rements may be used in the evaluation of an unexplained
abnormal level of either of these markers [5, 6]. PLGF
is a dimeric glycoprotein that is secreted to maternal
blood and is capable of strong angiogenic and mitogenic
activities that in turn can induce the proliferation, mig-
ration, and activation of endothelial cells [12]. In 2008
Akolekar et al. [1] have found that significant contribu-
tions for the prediction of PE were provided by maternalcharacteristics and obstetric history, serum PLGF and
uterine artery pulsatility index (PI) measured at 11-14
weeks of gestation and with combined screening the de-
tection rates for early PE and late PE were 90% and 49%,
respectively, for a false-positive rate of 10%.The authors
have suggested that effective screening for PE can be
provided by a combination of maternal characteristics
and obstetric history, uterine artery PI and maternal
serum PLGF at 11 + 0 to 13 + 6 weeks' gestation.
Our objective was to examine the possible relation-ship of PLGF measurements in late 1
st trimester of preg-
nancy with selected maternal clinical features, maternal
serum concentrations of pregnancy-associated plasma
protein-A (PAPP-A), free β-human chorionic gonado-
tropin (β-hCG) and various late pregnancy complications.
Methods
The study population included 113 singleton preg-
nant women who attended the prenatal screening prog-
ram in Lublin, between August 2009 and March 2010.
All pregnant women who accepted the first-trimester
screening test had blood drawn at the first visit at ul-
trasound screening unit between gestational weeks 11 +
0 days and 13 + 6 days. In each pregnant women ultra-
sound scan according to FMF guidelines was performed
with the use of transabdominal probe RAB 4-8 MHz of
the GE Voluson E8 scanner. Following parameters were
measured: fetal crown-rump length (CRL), biparietal dia-
meter (BPD), femur length (FL) and nuchal translucency
(NT) as well as fetal heart rate (FHR). Following ultra-
sound examination a venous blood sample was drawn in
each patient. All samples were centrifuged to separate
serum which was next was frozen in !80EC until further
analysis. The serum samples were analyzed at Multimed
(Warsaw) laboratory. Levels of PAPP-A and free β-hCG
were determined by the Delfia Express (Perkin Elmer,
Turku, Finland) method and registered in the electronic
database of biochemical test results by the unique pa-
tient identifier. The PAPP-A and free β-hCG serum va-
lues were converted to multiples of the median (MoM)
values by expressing the absolute concentration relative
to the median value for the gestational age at the day of
blood sampling. MoM values were corrected for mater-
nal weight (as a continuous variable). PLGF was mea-
sured with an ELISA method. A second ultrasound exa-
mination was performed again in weeks 18-22, when the
fetus was examined for structural abnormalities; specific
measures were recorded in the clinical database. The
scans were all performed by sonographers certified to
perform NT measurement by The Fetal Medical Foun-dation, London, UK. Data regarding all variables derived
from the ultrasound measures in the antenatal screening
program as well as the biomarkers were obtained from
the Astraia Database (www.astraia.com), which is a data-
base developed for clinical purposes such as documen-
tation and individual risk assessment. Only certified
sonographers and medical doctors have access to type in
data in the Astraia Database.
Information about delivery week and neonatal birth
weight at delivery, as well as possible delivery complica-tions was obtained from women themselves or from the
hospital data bases. The registration forms were comple-
ted by the attending midwife, further they were manually
checked and compared with the medical charts by a re-
search midwife, before data entry. Multiple logistic reg-
ression analyses and other statistical tests were used as
appropriate to estimate a potential explanation of the
association of other variables (maternal age, maternal
body mass index (BMI), week at delivery, fetal biometry,
MoM’s of PAPP-A and free beta HCG, neonatal weight).
The statistical software package STATISTICA v.6.0 (Stat-
soft,USA) was used for the data analyses. Value p of <
0.05 was considered statistically significant.
Results
Mean age of studied women was 38.8 years (range:
16 to 42 years). Mean neonatal weight at delivery was
3367 g (median – 3460 g, min-max 150-5660 g). Mean
body mass index (BMI) value of studied pregnant women
was 24.3±4.1 (min-max: 18.4-38.2). Fetal crown-rump
length (CRL) ranged from 45 mm to 83 mm and measu-
red nuchal translucency (NT) values ranged from 1,01 to
3.1 mm (median – 1.91 mm). Median maternal serum
PLGF concentration was 32.38 pg/ml (interquartile
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Placental growth factor (PLGF) with PAPP-A and free beta hCG assessment 201
Table 1. Means and medians of PLGF serum concentrations in early gestation
Weeks of gestation SD MDRange
(Min-max.)Interquartile range P value
11wekks + 0 days to 11weeks+ 6days 47,9 39,9 15.9-139 25.9-48.3H = 1.53;
p = 0.46
12weeks+0 days to 12 weeks + 6 days 57.1 32.9 10.9-593 24.3-56.4
13weeks + 0 days to13weeks + 6 days 44.1 31.8 10.1-253 21-40
Table 2. Selected clinical, sonographic and biochemical parameters with birth weight characteristics and pregnancy
complications compared to PLGF levels in late 1st trimester of gestation
NumberNeonatal birth weight
(median and range)
Statistical
analysis
PLGF pg/ml
(median, range)
Statistical
analysis
No complications N = 90 3456 g (2010 g-5660 g) Z = 0.9;
p = 0.33
34.9 (24.3-48.7) Z = 1.95;
p = 0.05Complications N = 23 3350 g (2700 g-3790 g) 25.5 (22.3-34.2)
Type of delivery
Normal vaginal delivery N = 52 3600 g (3200 g-3850 g) Z = !2.68; p = 0.007
33.9 (24.6-48.7) Z =!0.68; p = 0.49Cesarean section N = 61 3360 g (2800 g-3620 g) 32.2 (22.3-46.2)
Hypertensive disorders of pregnancy
No hypertension N = 107 3450 g (3100 g-3705 g) Z = !1.28;
p = 0.19
33.3 (23.6-47.6) Z = 0.5;
p = 0.5Hypertensive disorders in late gestation N =6 3715 g (3360 g-4050 g) 30.1 (23.8-36.4)
Time of delivery
Term delivery N =104 3480 g (3180 g-3800 g) Z =3 .6;
p = 0.0003
33.4 (23.8-47.6) Z = 0.5;
p = 0.5Preterm delivery(< 37 weeks) N = 9 2600 g (2420 g-3170 g) 27.6 (18.2-46.6)
range: 23.6-46.6 pg/ml, SD = 51.18 pg/mol, min-max =10.1-593.5 pg/ml). Median concentrations of PLGF de-
creased with the increase of gestational age. During the
11th week of gestation the median PLGF level was 39.9
pg/ml (range: 25.9-48.3 pg/ml), whereas in the 12th week
of gestation the median level was 32.9 pg/ml (range:
24.3-56.4 pg/ml). In the 13th week of gestation the
median serum PLGF concentration was 31.8 pg/ml (ran-
ge: 21-40 pg/ml). These values were not statistically dif-
ferent between particular weeks of pregnancy (H = 1.53;
p = 0.46). Normal vaginal delivery occurred in 52 women
of the studied group and there were 61 cesarean sec-
tions performed for various indications. There were two
stillbirths and 2 neonates were born alive with severe
genetic disorders, one Down syndrome and one Turner
syndrome. Nineteen other pregnancies had minor obs-
tetrical or neonatal complications at delivery.
Calculated multiples of the medians (MoM’s) of free
beta HCG and PAPP-A were 0.73 (range: 0.51-1.07) and
3.08 (range: 1.81-4.94), respectively. Spearman’s rank
correlation test indicated statistically significant corre-
lation between maternal serum PLGF concentrations
and fetal CRL in the late 1st trimester of gestation R =
0.19; p = 0.04). No statistically significant correlations
were found between maternal serum PLGF levels and
other studied parameters such as: maternal BMI, fetalNT, and calculated MoM’s of free beta HCG as well as
PAPP-A in maternal serum (all p ’s > 0.005).
Median serum PLGF concentrations in a group of
women with no pregnancy complications was 34.9 pg/ml
(range: 24.3-48.7 pg/ml), whereas in women with any
detected pregnancy complication and/or congenital birth
defects the median PLGF concentration was 25.5 pg/ml
(22.3-34.2 pg/ml). The differences between these groups
were close to statistically significant correlation (Z =
1.95; p = 005). However, the median birth weight did not
differ significantly between both groups (Z = 0.9; p =
0.33).
There were 6 cases of pregnancy induced hyperten-
sion in the studied group. The median PLGF serum
concentrations did not differ between these groups (Z =
0.5; p = 0.5). No significant difference was found bet-
ween the medians of neonatal birth weights (Z = !1.28;
p = 0.19).Term delivery occurred in 104 women of the
studied group and 9 women had preterm delivery. Again,
the medians of PLGF maternal serum concentrations did
not differ between these groups (Z = 0.5; p = 0.5).
Median neonatal birth weight was significantly higher in
women with term deliveries (Z = 3.6; p = 0.0003). The
mode of delivery either vaginal or cesarean section was
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A. Czekierdowski, S. Czekierdowska, A. Krzy ż anowski et al.202
not correlated with the late 1st trimester maternal serum
PLGF concentrations (Z = !0.68; p = 0,49). The median
neonatal birth weight following vaginal delivery was signi-
ficantly higher than the median birth weight following
cesarean section delivery (Z =!2.68; p = 0.007). Spear-
man’s rank correlation test indicated no significant corre-
lations between early pregnancy maternal PLGF con-
centrations and neonatal birth weight R = 0.1; p = 0.29).
Discussion
There is an increasing evidence that various fetal
and maternal late pregnancy complications might be
established in early 1st trimester. Recently, it has been
postulated that the combination of slow early fetal
growth and low PAPP-A resulted in a nearly six-fold in-
creased risk of delivery of an SGA infant [9]. In the first trimester, an unexplained low PAPP-A (< 0.4 MoM)
and/or a low hCG (< 0.5 MoM) are associated with an
increased frequency of adverse obstetrical outcomes,
and, at present, no specific protocol for treatment is
available [17]. It has been recently shown that decreased
PlGF levels were observed prior to 20 weeks of gesta-
tion in women who subsequently develop preeclampsia
[18, 19].
Cowans et al. [2] suggested that low levels of first-
trimester PLGF provide a good indicator of SGA compli-
cations and some hypertensive disorders, in particular
severe cases of PE such as early onset and HELLP synd-
rome. Low levels of placental growth factor expressed as
the lowest third centile at both samplings was associated
with high risk of SGA with the odds ratio of 3.8 and 95%
confidence interval of 1.6- 8.8 [15]. Also, if the increase
from the lowest to the highest third of soluble Flt-1 was
found in examined samples, there was a substantial
increase in SGA neonate risk with the odds ratio of 6.2
with 95% confidence interval of 2.4-16.1. In the same
study women with high soluble endoglin serum concen-
tration expressed as the highest third centile at the
second sampling had approximately a 3.5-fold increased
risk of SGA. The authors have concluded that the finding
of low maternal soluble Flt-1 in early pregnancy subse-
quently followed by an increase in soluble Flt-1 and rise
in soluble endoglin concentrations was associated with
a significantly increased risk of severe fetal growth re-
striction in late pregnancy. These findings might impro-
ve our chances of early identification of fetuses at in-
creased risk of growth restriction. In such selected highrisk cases increased pregnancy surveillance might re-
duce the risk of adverse fetal outcome and maternal
pregnancy related disease.
It is possible that new modalities of non-invasive
examination might prove more cost-effective to imple-
ment methods for the early identification of fetuses at
high risk of later adverse outcome than to offer third-
trimester ultrasound scans with fetal weight estimation
to the entire population. Since PAPP-A, free β-hCG and
measures of early fetal growth are already assessed in
pregnant women participating in prenatal screening
programs, the use of these modalities in early identifi-
cation would be at no or relatively small extra cost [5, 9,
19]. Early risk assessment might be based on PAPP-A,
free β-hCG and PLGF, perhaps combined with maternal
blood pressure measurements with other serum mar-
kers, uterine artery Doppler flow assessment [4, 14].
There are also some new possibilities of three-dimen-
sional ultrasound measures of placental volume and vas-cular blood flow.
When increased risk for PE development is found it
is crucial to plan both pregnancy surveillance strategy
and pharmacological treatment options. Treatment stra-
tegies may include antihypertensive drugs, low salt and
non saturated fatty acid rich diet and most of all more
frequent non-invasive biochemical and sonographic te-
sting of pregnancy status. The findings of our study sup-
port the view that combined measurements of PAPP-A,
f-beta hCG and PLGF are highly valuable tool for thenon-invasive detection of PE risk group. In such cases an
exact diagnosis followed by possibly best adjusted and
timely intervention, for example aspirin/ heparin treat-
ment or induction of fetal lung maturation would be
potentially of a great value in decreasing the frequency
of the most serious preeclampsia complications. More-
over, a recruitment for future studies searching new the-
rapeutic interventions and additional prospective mar-
kers could be improved. Understanding relations among
maternal characteristics and levels of angiogenic factors
may help to design studies that use these markers to
examine etiology and to predict potential adverse preg-
nancy outcome. Production and concentration of various
biomarkers are ultimately dependent on genetic factors.
It has been suggested that new genomic studies are
likely to detect genetic variants associated with pre-
eclampsia. However, in contrast to the static genome,
the proteome is dynamic. Whereas the genome will not
change during pregnancy or pregnancy-associated condi-
tions such as preeclampsia, the proteome could be chan-
ged by various modifying internal and environmental fac-tors. It is therefore likely that new proteomic and meta-
bolomic studies that will use a large number of biomar-
kers will be able to indicate these truly effective in scree-
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Placental growth factor (PLGF) with PAPP-A and free beta hCG assessment 203
ning molecules. These markers could potentially be
more accurate in predicting increased risk of preeclamp-
sia than time-consuming and costly genomic studies. Ob-
viously, larger studies are needed to confirm these find-
ings.
Our prenatal screening program covers the popula-
tion in a large area and is free of charge. Accordingly, we
believe that our study population is highly represen-
tative, without oversampling of high-risk pregnancies.
Despite the limitations in sample size and exploratory
nature of the study, we conclude that placental growth
measurements in the late 1st trimester in pregnant wo-
men blood serum may provide additional prognostic
value in predicting various late pregnancy complications
including preeclampsia. Based on published evidence
and on our current study results we believe that a panelof markers presented above may be used in clinical prac-
tice to detect women at increased risk of preeclampsia.
Obviously, further studies are required before any firm
conclusion can be reached.
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J Artur Czekierdowski
Ist Department of Gynecological Oncology
and Gynecology
Medical University in Lublin
20-081 Lublin, Staszica 16
e-mail: [email protected]