The effect of Rhesus status on first-trimester pregnancy screening markers free beta human chorionic gonadotropin, pregnancy-associated plasma protein-A and nuchal translucency.
ABSTRACT To examine whether maternal Rhesus status has any effect on the levels of first-trimester markers free beta-human chorionic gonadotropin (beta-hCG), pregnancy-associated plasma protein-A (PAPP-A) and nuchal translucency (NT).
First-trimester free-beta-hCG and PAPP-A levels from pregnant women attending three hospitals in Kent were converted into MoMs and corrected for maternal weight, ethnicity, and smoking status. Maternal Rhesus status data were merged with screening data and free-beta-hCG and PAPP-A medians multiples of medians (MoMs) and NT from the Rhesus positive and Rhesus negative group were compared.
Totally, 15 045 normal, singleton pregnancies were retrieved with full records. Altogether, 16.0% of the population were Rhesus negative. There was no difference between the medians MoMs of both free-beta-hCG nor PAPP-A nor NT in the two Rhesus status groups (p > 0.05). Demographic analysis on the distribution of Rhesus status in different ethnic origins showed that Caucasians have lower percentages of RhD-positive antigen compared to Asians and Afro-Caribbeans.
Maternal Rhesus status does not influence the levels of free-beta-hCG and PAPP-A in the first trimester of pregnancy in this almost exclusively Caucasian population studied; therefore correction for maternal Rhesus status is not suggested.
- SourceAvailable from: Kerem Doğa Seçkin[Show abstract] [Hide abstract]
ABSTRACT: Abstract Objective: To determine whether inherited thrombophilia affects components of first trimester combined aneuploidy screening test. Method: A case-control study was performed between January 1(st) and December 31(st) 2011, at a tertiary referral hospital. Singleton pregnancies with inherited thrombophilia that underwent first trimester (11-13(+6) week) combined aneuploidy screening test were included in the study. Pregnancy associated plasma protein-A (PAPP-A), free beta-human chorionic gonadotropin (fbHCG) and fetal nuchal translucency (NT) were compared between the study group and controls. Results: Within the study period, 15,881 women with singleton pregnancies had a combined first trimester aneuploidy screening test at our institution. Among these, 207 women met the inclusion criteria. A control group that comprised 625 women with similar gestational age was generated, using a 1:3 ratio. PAPP-A levels were significantly higher, whereas fbHCG levels and fetal NT measurements were lower in women with inherited thrombophilia (p<0.001). Conclusion: Our study suggested that PAPP-A, free b-HCG and NT MoM levels display alterations in women with inherited thrombophilia. Future trials are needed to assess the need for readjustment of risk in these patients.The journal of maternal-fetal & neonatal medicine: the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians 06/2013; · 1.36 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Abstract Objective: Reliability of first and second trimester screening tests largely depends on accurate estimation of maternal serum marker values. Reduced reliability could lead redundant invasive tests or misdiagnosis. Adjustments of serum marker values for confounding factors like insulin dependent diabetes, maternal weight or maternal rhesus status are essential. We aimed to investigate whether isolated single umbilical artery alters first and second trimester test parameters or not. Methods: Routine detailed obstetric ultrasonographies performed were retrospectively screened for this study. Amongst spontaneously conceived singleton pregnancies, women that were found to have single umbilical artery without any additional structural anomalies or aneuploidies were selected. First and second trimester screening test results were accessible for 98 and 102 of the cases with isolated single umbilical artery respectively. Results: Amongst first trimester screening test parameters, PAPP-A (Pregnancy associated plasma protein A) MoMs were found significantly higher in isolated single umbilical artery group. AFP MoMs were found significantly elevated in isolated single umbilical artery group in second trimester quadruple tests. Conclusion: Existence of single umbilical artery could alter the estimation of MoM values of maternal serum markers. Reliability of prenatal screening tests could be improved by adjusting these parameters in accordance with isolated single umbilical artery.Journal of Maternal-Fetal and Neonatal Medicine. 05/2014;
Prenat Diagn 2009; 29: 505–507.
Published online 16 February 2009 in Wiley InterScience
(www.interscience.wiley.com) DOI: 10.1002/pd.2231
The effect of Rhesus status on first-trimester pregnancy
screening markers free β human chorionic gonadotropin,
pregnancy-associated plasma protein-A and nuchal
Nicholas J. Cowans, Anastasia Stamatopoulou and Kevin Spencer*
Prenatal Screening Unit, Department of Clinical Biochemistry, King George Hospital, Essex IG3 8YB UK
free beta-human chorionic gonadotropin (β-hCG), pregnancy-associated plasma protein-A (PAPP-A) and
nuchal translucency (NT).
To examine whether maternal Rhesus status has any effect on the levels of first-trimester markers
Kent were converted into MoMs and corrected for maternal weight, ethnicity, and smoking status. Maternal
Rhesus status data were merged with screening data and free-β-hCG and PAPP-A medians multiples of medians
(MoMs) and NT from the Rhesus positive and Rhesus negative group were compared.
First-trimester free-β-hCG and PAPP-A levels from pregnant women attending three hospitals in
the population were Rhesus negative. There was no difference between the medians MoMs of both free-β-hCG
nor PAPP-A nor NT in the two Rhesus status groups (p > 0.05). Demographic analysis on the distribution
of Rhesus status in different ethnic origins showed that Caucasians have lower percentages of RhD-positive
antigen compared to Asians and Afro–Caribbeans.
Totally, 15045 normal, singleton pregnancies were retrieved with full records. Altogether, 16.0% of
trimester of pregnancy in this almost exclusively Caucasian population studied; therefore correction for maternal
Rhesus status is not suggested. Copyright 2009 John Wiley & Sons, Ltd.
Maternal Rhesus status does not influence the levels of free-β-hCG and PAPP-A in the first
KEY WORDS: aneuploidy screening; combined test; Rhesus status; free beta-hCG; PAPP-A; nuchal translucency
The most effective screening program for fetal chromo-
somal abnormalities is a combination of first-trimester
fetal nuchal translucency (NT) measurements, first-
trimester maternal serum free beta-human chorionic
gonadotropin (free-β-hCG), and pregnancy-associated
plasma protein-A (PAPP-A) measurements, combined
with the maternal age specific risk (Spencer et al.,
1999). Certain factors influence the levels of these mark-
ers, including maternal ethnic origin (Spencer et al.,
2000, 2005), maternal weight (Spencer et al., 2003),
maternal smoking status (Kagan et al., 2007; Spencer,
1999; Spencer et al., 2004), and multiple pregnancies
(Spencer, 2000; Spencer et al., 2008; Spencer and Nico-
laides, 2003). Evaluation of risk for fetal anomalies will
commonly use an algorithm which corrects for these fac-
tors, in order to give the most accurate screening risk.
It is possible that other factors, not yet included
in such algorithms, may influence the levels of first-
trimester screening markers to a degree which could alter
the final screening risk.
Presence or absence of maternal Rhesus D antigen
(Rhesus status) is measured in most pregnancies because
*Correspondence to: Kevin Spencer, Prenatal Screening Unit,
Department of Clinical Biochemistry, King George Hospital,
Essex IG3 8YB UK. E-mail: email@example.com
of the risks caused by Rhesus D incompatibility in
Rhesus negative mothers. Studies in the first (Muhcu
et al., 2008) and second trimester (Muhcu et al., 2007;
Sancken and Bartels, 2001) have shown differences
in the levels of free-β-hCG and unconjugated oestriol
(uE3) in Rhesus negative women. In a previous smaller
study, looking also at ABO blood groups, we have
shown that B Rhesus positive women had statistically
higher levels of PAPP-A in first-trimester pregnancies,
but no difference was found in free-β-hCG levels, or in
either markers when looking at ABO or Rhesus status
alone (Cowans and Spencer, 2007).
In the present study, we use a larger sample size
to further investigate whether Rhesus status has any
effect on levels of maternal serum markers used in
first-trimester screening, and, if significant, whether any
change might require the inclusion of Rhesus status
correction in screening algorithms for fetal chromosomal
anomaly risk assessment.
MATERIALS AND METHODS
Data from women attending routine first-trimester pre-
natal screening at Queen Elizabeth the Queen Mother
Hospital, Kent, William Harvey Hospital, Kent and Kent
and Canterbury Hospital, Kent with births between Jan-
uary 1999 and December 2007 were included in the
Copyright 2009 John Wiley & Sons, Ltd.
Received: 12 December 2008
Revised: 7 January 2009
Accepted: 15 January 2009
Published online: 16 February 2009
N. J. COWANS ET AL.
Screening data were collected in the first trimester
(11–13 + 6 weeks) and stored in a central database.
Blood samples from women attending each hospital in
Kent were separated in the local pathology laboratory
and sent via post to screening laboratory at Harold Wood
Hospital, Essex (1999–2006) or at King George Hospi-
tal, Essex (2007 onwards) for biochemical assessment.
Maternal serum free-β-hCG and PAPP-A were measured
using the Kryptor analyser (Brahms AG, Berlin) and the
performance of this assay has been previously described
(Spencer et al., 1999). Fetal NT and crown rump length
measurements were undertaken during the routine first-
trimester ultrasound scan and the blood sample was
collected on the same day Using patient-specific ges-
tational age at screening, maternal serum markers were
converted to MoMs and corrected for maternal weight
(Spencer et al., 2003), smoking status (Spencer et al.,
2004), and ethnicity (Spencer et al., 2000, 2005).
Maternal Rhesus status was determined by the local
pathology laboratory and was appended to birth records
by the hospital where the delivery occurred and stored in
a separate birth records database. A structured database
query language (SQL) query was created to join screen-
ing and birth records. The selection criteria were: to
match mothers, either (1) surname, first five letters of the
forename (to allow for typographical errors), and date
of birth (DOB), or (2) surname and hospital number, or
(3) first five letters of forename and hospital number (to
allow for changing of surnames from marriage). Also, to
match pregnancies, the date of conception derived from
gestational age at screening and at birth had to be within
30 days to ensure the same pregnancy was selected for
the individual woman match.
The mean of the log10-transformed MoMs of PAPP-
A and free-β-hCG was compared using two-tailed
t-tests for independent samples. NT was evaluated
using the Mann–Whitney test. Demographic data were
evaluated using Mann–Whitney test and Chi-squared
test. Statistical significance was set at 0.05. Softwares
used: MySQL Community Server (version 5.0, MySQL
AB, Uppsala, Sweden), SPSS (SPSS Inc., Chicago,
During the period studied, 15045 normal, singleton
pregnancies that resulted in normal live birth with
full records for first-trimester PAPP-A and free-β-hCG
MoMs and maternal Rhesus blood group data were
retrieved. Of these, 84.0% were Rhesus positive and
16.0% were Rhesus negative.
Table 1 shows the demographic data for this study
group. Table 2 shows a comparison of the median
marker MoM levels in Rhesus positive and negative
sets of the population, and the p value from comparison
of the log10MoM levels. For NT, there was also
Table 1—Demographic data for each Rhesus blood group
population in this study
Rhesus Negative Rhesus Positive
Maternal weight (kg)
Maternal age (years)
Gestational age (days)
Ethnic Origin (%)
Table 2—Median NT and MoM values for free-β-hCG and
PAPP-A in Rhesus negative and positive
Table 3—Percentage of Rhesus negative or Rhesus positive
mothers in each ethnic origin group
Rhesus negativeRhesus positive
Ethnic Origin (%)
p < 0.0001.
no difference between the two populations. None of
the demographic characteristics and screening marker
levels were statistically significantly different between
the Rhesus positive and negative groups. Table 3 shows
the percentages of Rhesus positive and negative mothers
in each ethnic origin group.
This study has found that the first-trimester serum
markers levels of free-β-hCG and PAPP-A and NT
do not differ in Rhesus positive and Rhesus negative
women. Two other studies have also looked at the same
biomarkers in relationship to Rhesus status using smaller
Using a considerably smaller sample size (n = 2252),
we previously have studied the effect Rhesus and ABO
blood group status has on free-β-hCG and PAPP-A
(Cowans and Spencer, 2007). Looking at each individual
blood group alone and as a combination of Rhesus
and ABO status, we found no significant differences
comparing each group with the whole population for
Copyright 2009 John Wiley & Sons, Ltd.
Prenat Diagn 2009; 29: 505–507.
EFFECT OF RHESUS STATUS ON FIRST-TRIMESTER PREGNANCY SCREENING MARKERS
free-β-hCG, and only found a significant increase in
PAPP-A in the B Rhesus positive group (Median MoM
0.937 vs. 0.995), which would not have been found to be
significant had the chosen significance cut-off been 0.01,
a value perhaps more appropriate for a study comparison
such as was undertaken.
More recently, another smaller sample size study (n =
2200) reported a statistically significant increase in free-
β-hCG levels in Rhesus negative women compared with
Rhesus positive women (Muhcu et al., 2008), suggesting
that Rhesus incompatibility may be responsible for this
Since the current study draws upon a much larger
sample population, it would be tempting to suggest that
the previous small sample sizes were an explanation
for the discrepancies. However, one must consider
the possibility of a variation in ethnic make up of
each population being responsible for the observed
differences between the studies.
In this study, we have shown that the percentage
of Rhesus negative Caucasian women is higher than
Asian, Afro–Caribbean and other nonCaucasian women.
This finding has been supported elsewhere (Garratty
et al., 2004). Compared to Caucasians, Afro–Caribbean
women have previously been shown to have an increased
level of free-β-hCG and Asians have been shown to
have a decreased level of free-β-hCG (Spencer et al.,
2000, 2005). Therefore a variation in ethnic make up
of a population could potentially cause a change in
marker levels which may be misinterpreted as being
caused by the Rhesus status due to masking. In the
case of Muhcu et al., all subjects were from the same
population in Istanbul, Turkey, and the percentage of
Rhesus positive women was considerably smaller than
found in our population (7.3 vs. 16.0%, Istanbul vs.
Kent). However, since corrections for ethnic origin were
made at time of screening in Kent and the entire Istanbul
sample population was of the same ethnic group, it is
unlikely that this is an explanation for the differences
between the studies.
Since we were able to show no link between Rhesus
status and first-trimester serum markers, we suggest no
further adjustments to first-trimester screening should be
carried out in populations such as our own. More studies
are needed to evaluate any potential role of Rhesus status
in first-trimester populations with a higher proportion of
Cowans NJ, Spencer K. 2007. Is there an association between
maternal ABO and rhesus blood groups and the first-trimester serum
markers free beta-hCG and PAPP-A used for the detection of fetal
aneuploidy? Prenat Diagn 27: 64–67.
Garratty G, Glynn SA, McEntire R. 2004. ABO and Rh(D) phenotype
frequencies of different racial/ethnic groups in the United
States.Transfusion 44: 703–706.
Kagan KO, Frisova V, Nicolaides KH, Spencer K. 2007. Dose
dependency between cigarette consumption and reducead maternal
serum PAPP-A levels at 11–13 + 6 weeks of gestation. Prenat
Diagn 27: 849–853.
Muhcu M, Mungen E, Atay V, et al. 2008. First trimester screening
for Down syndrome in rhesus negative women. Prenat Diagn 28:
Muhcu M, Mungen E, Dundar O, et al. 2007. Reliability of second
trimester triple screening for Down syndrome in rhesus-negative
women. J Perinatol 27: 268–271.
Sancken U, Bartels I. 2001. Preliminary data on an association
between blood groups and serum markers used for the so-called
“triple screening”: free oestriol MoM values are decreased in
rhesus-negative (Rh-) women. Prenat Diagn 21: 194–195.
Spencer K. 1999. The influence of smoking on maternal serum PAPP-
A and free beta hCG levels in the first trimester of pregnancy.
Prenat Diagn 19: 1065–1066.
Spencer K. 2000. Screening for trisomy 21 in twin pregnancies in
the first trimester using free beta-hCG and PAPP-A, combined with
fetal nuchal translucency thickness. Prenat Diagn 20: 91–95.
Spencer K, Bindra R, Cacho AM, Nicolaides KH. 2004. The impact
of correcting for smoking status when screening for chromosomal
anomalies using maternal serum biochemistry and fetal nuchal
translucency thickness in the first trimester of pregnancy. Prenat
Diagn 24: 169–173.
Spencer K, Bindra R, Nicolaides KH.
correction of maternal serum PAPP-A and free beta-hCG MoM
when screening for trisomy 21 in the first trimester of pregnancy.
Prenat Diagn 23: 851–855.
Spencer K, Heath V, El-Sheikhah A, Ong CY, Nicolaides KH. 2005.
Ethnicity and the need for correction of biochemical and ultrasound
markers of chromosomal anomalies in the first trimester: a study of
Oriental, Asian and Afro-Caribbean populations. Prenat Diagn 25:
Spencer K, Kagan KO, Nicolaides KH. 2008. Screening for trisomy
21 in twin pregnancies in the first trimester: an update of the
impact of chorionicity on maternal serum markers. Prenat Diagn
Spencer K, Nicolaides KH. 2003. Screening for trisomy 21 in twins
using first trimester ultrasound and maternal serum biochemistry in
a one-stop clinic: a review of three years experience. BJOG 110:
Spencer K, Ong CY, Liao AW, Nicolaides KH. 2000. The influence
of ethnic origin on first trimester biochemical markers of
chromosomal abnormalities. Prenat Diagn 20: 491–494.
Spencer K, Souter V, Tul N, Snijders R, Nicolaides KH. 1999.
A screening program for trisomy 21 at 10–14 weeks using
fetal nuchal translucency, maternal serum free beta-human
chorionic gonadotropin and pregnancy-associated plasma protein-
A. Ultrasound Obstet Gynecol 13: 231–237.
Copyright 2009 John Wiley & Sons, Ltd.
Prenat Diagn 2009; 29: 505–507.