The comparison of intelligence levels of children born to kidney or liver transplant women with children of healthy mothers

Abstract

Background: Pregnancy after transplantation is associated with high risk of complications and prenatal exposure to immunosuppressants. The purpose of the study was to evaluate the intellectual development of children born to women after organ transplantation.
Aims: A comparison of intelligence levels in 78 children of kidney or liver transplant women of 78 children born to healthy mothers. The assessment of intellectual level in children was conducted by psychologists and evaluated using age-adjusted intelligence tests (Psyche Cattell Infant Intelligence Scale, Terman-Merril Intelligence Scale or the Scales of Raven’s Progressive Matrices).
Results: No significant differences in the distribution of the quotient of intelligence between children born to kidney and liver transplant women were noted (chi² = 5.037; p = 0.284). Also no differences in the distribution of intelligence levels was noted between the children of transplanted and healthy mothers in infants and toddlers (chi² = 3.125; p = 0.537); preschool (chi² = 1.440; p = 0.692) and school age children (chi² = 4.079; p = 0.395).
Conclusions: The intellectual development of children of post-transplant women is similar to the general population. These results provide information on the low risk of intellectual disability in children of transplanted mothers and may improve counseling on the planning of pregnancy in this group of women.

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The comparison of intelligence levels of children
born to kidney or liver transplant women with
children of healthy mothers
Bozena Kociszewska-Najman, Monika Szpotanska-Sikorska , Natalia
Mazanowska, Miroslaw Wielgos & Bronislawa Pietrzak
To cite this article: Bozena Kociszewska-Najman, Monika Szpotanska-Sikorska , Natalia
Mazanowska, Miroslaw Wielgos & Bronislawa Pietrzak (2017): The comparison of intelligence
levels of children born to kidney or liver transplant women with children of healthy mothers, The
Journal of Maternal-Fetal & Neonatal Medicine, DOI: 10.1080/14767058.2017.1365131
To link to this article: http://dx.doi.org/10.1080/14767058.2017.1365131
Accepted author version posted online: 07
Aug 2017.
Published online: 16 Aug 2017.
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ORIGINAL ARTICLE
The comparison of intelligence levels of children born to kidney or liver
transplant women with children of healthy mothers
Bozena Kociszewska-Najman
a
, Monika Szpotanska-Sikorska
b
, Natalia Mazanowska
b
,
Miroslaw Wielgos
b
and Bronislawa Pietrzak
b
a
Neonatology Ward, 1st Department of Obstetrics and Gynecology, Medical University of Warsaw, Warszawa, Poland;
b
1st Department of Obstetrics and Gynecology, Medical University of Warsaw, Warszawa, Poland
ABSTRACT
Background: Pregnancy after transplantation is associated with high risk of complications and
prenatal exposure to immunosuppressants. The purpose of the study was to evaluate the intel-
lectual development of children born to women after organ transplantation.
Aims: A comparison of intelligence levels in 78 children of kidney or liver transplant women of
78 children born to healthy mothers. The assessment of intellectual level in children was con-
ducted by psychologists and evaluated using age-adjusted intelligence tests (Psyche Cattell
Infant Intelligence Scale, Terman–Merril Intelligence Scale or the Scales of Raven’s Progressive
Matrices).
Results: No significant differences in the distribution of the quotient of intelligence between
children born to kidney and liver transplant women were noted (Chi
2
¼5.037; p¼.284). Also no
differences in the distribution of intelligence levels were noted between the children of trans-
planted and healthy mothers in infants and toddlers (Chi
2
¼3.125; p¼.537); preschool
(Chi
2
¼1.440; p¼.692), and school age children (Chi
2
¼4.079; p¼.395).
Conclusions: The intellectual development of children of post-transplant women is similar to
the general population. These results provide information on the low risk of intellectual disability
in children of transplanted mothers and may improve counseling on the planning of pregnancy
in this group of women.
ARTICLE HISTORY
Received 16 July 2017
Revised 30 July 2017
Accepted 4 August 2017
KEYWORDS
Intelligence Quotient (IQ)
scale; mental development;
transplantation
Introduction
Mental development is a complex, dynamic process
that has its beginning in early pregnancy [1]. The most
intense mental development takes place in the pre-
natal life and then during infancy and early childhood,
when intelligence and socialization are created.
The mental disturbances (transient or permanent)
may occur in early period after the delivery or at later
stages of life. Sings of mental development may be
observed already in the early prenatal period. At the
later stage, around the fifth month of pregnancy, the
fetus may feel various sensory stimuli. In the seventh
month of pregnancy the fetus not only notice and
react to stimuli, but also differentiate and memorize
them. Mental impairment may be caused by brain
microtraumas, which can be triggered by various fac-
tors that may occur both in the pre- and postnatal
period [2].
The development of a transplant medicine
improved quality of life and gave women with the
end-stage organ failure a chance to become a mother.
However, pregnancy after transplantation is associated
with high risk of complications and prenatal exposure
to immunosuppressants [3,4]. In the literature, there is
a lack of studies evaluating the intellectual develop-
ment of children born to post-transplant women.
Therefore, the purpose of this study was to evaluate
the intellectual development of children born to
women after organ transplantation and to compare
them with the results of healthy mothers’children.
Materials and methods
A single-center cohort study conducted between 2001
and 2013 in the First Department of Obstetrics and
Gynecology at Warsaw Medical University and
included 78 children born to women after kidney or
liver transplantation (study group) and the same num-
ber of children born to healthy mothers (control
group). In case, when a pregnant transplant recipient
CONTACT Monika Szpotanska-Sikorska mszpotanska@wp.pl 1st Department of Obstetrics and Gynaecology, Medical University of Warsaw,
Warsaw, Poland
ß2017 Informa UK Limited, trading as Taylor & Francis Group
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gave birth to a child and agreed to participate in the
study, then a child born at the similar time by a
healthy mother was included in the control group. The
main criterion for the selection of control children was
the same gestational age at the time of childbirth as
in children born by post-transplant women. A proper
selection of a control group in this respect might
reduce potential differences in intelligence assessment,
due to possible differences in the gestational age at
the time of childbirth. Parents of enrolled children
have signed a voluntary consent to participate their
children in the study. The intelligence testing was one
of the components of a comprehensive assessment of
the health and developmental status of post-transplant
women’s children, which was supported by the Polish
Ministry of Science and Higher Education under Grant
[No. N407 534938/10].
The psychological examination was performed by
qualified clinical psychologists in years 2011–2015.
During that time, the children of post-transplant moth-
ers and appropriately selected children of healthy
women were invited to measure the intelligence lev-
els. The earlier selection of children in both studied
groups, who had an intellectual development assess-
ment at a similar time interval from the moment of
childbirth, made it possible to reliably compare the
obtained results. The following tests were used to
evaluate mental ability assessment: Psyche Cattell
Infant Intelligence Scale, Terman-Merril Intelligence
Scale or the Scales of Raven’s Progressive Matrices.
Each child was examined using one of the three tests
selected according to the child’s age at the time of
the test. The Cattell Infant Intelligence Scale is
designed to evaluate mental development of children
up to 30 months of age but it also includes elements
for evaluating older children aged 36, 42, and 48
months. The scale contains items on object manipula-
tion, visual perception and visual motor integration,
voice reaction and spontaneous speech, reaction to
auditory stimuli, understanding of words, sentences
and short communications as well as social behaviors.
The scale allows the assessment of mental ability in
children with inharmonious development, with skills in
specific areas going beyond their age [5].
The assessment of intellectual ability in preschool
children aged from 2 to 7 years was conducted using
the Terman-Merrill Intelligence Scale. This scale con-
tains elements of verbal and non-verbal assessment
appropriate for each year of life. These are based on
the evaluation of spontaneous speech and compre-
hension, manipulation of objects and visual–motor
integration, auditory memory and immediate recall,
thinking as well as grapho-motor skills [6].
In the case of school children, Raven graduates
were used to assess non-verbal intellectual abilities.
The standard version is designed for children over 10
years of age. For this study, Color Progressive Matrices
were used to assess non-verbal ability at three levels
in children aged 5–11 years. This scale allows the
measurement of deductions and logical reasoning, pat-
tern recognition, relationships between shapes, pro-
gressive pattern changes, figures rearrangements and
their distribution [7–9].
In each child, both in the study and control groups,
all elements were analyzed, comprising the evaluation
of mental development that is speech, thinking, verbal
comprehension, grasping and manipulation, memory,
visual processing, and grapho-motor skills.
The results of Intelligence Quotient (IQ) were classi-
fied and divided as follows: very high (IQ >130), high
(102–129), above average (110–119), mean (90–109),
and below average (80–89). The results of the IQ test
were statistically analyzed. The results are presented as
means with standard deviations or percentages. The
Chi-square test (chi
2
) with Yates correction, Student’s
t-test, and Fisher’s exact test were used to calculate
differences between groups. The level of statistical sig-
nificance was set at p¼.05. Statistical analyses were
performed using Statistica for Windows 8.0 (StatSoft,
Inc., Tulsa, OK).
Results
The study included 78 children born to mothers after
organ transplants, of which 42 (54%) were pregnancies
in women after liver transplant (LT) and 36 (46%) after
kidney transplant (KT) and the same number (78) of
children born to healthy mothers. Mothers in the con-
trol group were less likely to give birth by caesarean
section than mothers after organ transplants. However,
no significant differences were observed in the chil-
dren in the study group compared with the control
group in terms of gestational age, birth weight, hypo-
trophy, or preeclampsia (Table 1). The same number of
children in both groups was tested in three age-appro-
priate psychological tests at the time of the study
(Table 3).
Preliminary analysis included a comparison of the
results of tests on the quotient of intelligence between
subgroups of children born to kidney transplant
women with children of liver transplant women. We
did not find any significant differences in the distribu-
tion of the results of tests performed on the quotient
of intelligence between these two subgroups
(Chi
2
¼5.037; p¼.284). In both groups, the percen-
tages of children with IQ test score below and above
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average results were comparable and not statistically
significant (Table 2). Due to the lack of significant dif-
ferences in the distribution of intelligence quotient
between two subgroups, further analysis included a
comparison of children born to post-transplant moth-
ers (both from the kidney and liver groups) with chil-
dren born to healthy children.
In infants and toddlers, no differences were found
in Psyche Cattell Infant Intelligence Scale between the
study and the control groups (Chi
2
¼3.125; p¼.537).
In both groups, an average quotient of intelligence
was mostly often diagnosed, and the distribution of
frequencies of lower and higher (14% versus 20%;
p¼.489) than the average intelligence levels was
comparable and similar to the normal distribution
(Table 3).
The level of intelligence in preschool children was
analyzed with the use of the Terman-Merrill
Intelligence Scale. In this age category in children born
to post-transplant mothers, the average quotient of
intelligence was diagnosed more often (36% versus
23%, p¼.321), while in the control group, the high
and very high quotient intelligence results were more
frequently noted (32% versus 45%; p¼.353). However,
those differences were statistically insignificant.
Analysis of the distribution of intelligence quotient
results in the Terman-Merrill Intelligence Scale did not
show any significant differences (Chi
2
¼1.440; p¼.692).
Table 2. The comparison of IQ tests results between the study and control groups.
The IQ test result KT, n¼36
a
LT, n¼42
a
Study group (KTþLT), n¼78
b
Control group, n¼78
b
Below average n(%) 2 (6) 3 (7) 5 (6) 5 (6)
Average n(%) 17 (47) 14 (33) 31 (40) 24 (31)
Above average n(%) 8 (22) 12 (29) 20 (26) 27 (35)
High n(%) 9 (25) 9 (22) 18 (23) 13 (17)
Very high n(%) –4 (10) 4 (5) 9 (12)
KT: children of kidney transplant mothers; LT: children of liver transplant mothers; IQ: Intelligence Quotient.
a
Statistical value for the distribution of intelligence quotient results between the groups of children of liver transplant mothers
and children of kidney transplant mothers; Chi
2
¼5.037; p¼.284.
b
Statistical value for the distribution of intelligence quotient results between the groups of children of transplant mothers
(study group) and children of healthy mothers (control group); Chi
2
¼4.663; p¼.324.
Table 1. Characteristics of the study participants.
Variable Study group, n¼78 Control group, n¼78 pvalue
Factors associated with pregnancy
Mean gestational age at the time of childbirth (weeks) 37.0 ± 2.6 37.0 ± 2.8 >.999
Preeclampsia 4 (5) 4 (5) >.999
Mean birth weight of the newborn (g) 2653 ± 655 2880 ± 791 .053
Hypotrophy (<10 percentile), n(%) 9 (12) 5 (6) .402
Caesarean section 60 (70) 32 (40) <.001
Immunosuppressive drugs in pregnancy –
Tacrolimus, n(%) 40 (51) –
Cyclosporin, n(%) 20 (26) –
Azathioprine, n(%) 2 (3) –
Azathioprine and cyclosporine, n(%) 11 (14) –
Azathioprine and tacrolimus, n(%) 5 (6) –
Steroids, n(%) 66 (85) –
Table 3. Comparison of the results of individual psychological tests between the study group and the control group.
Psyche Cattell Infant Intelligence Scale 
infants and toddlers;
n(%)
a
Terman-Merril Intelligence Scale 
preschool children;
n(%)
b
Scales of Raven’s Progressive
Matrices –school children;
n(%)
c
IQ test result
Study group,
n¼31 (40)
Control group,
n¼31 (40)
Study group,
n¼22 (28)
Control group,
n¼22 (28)
Study group,
n¼25 (32)
Control group,
n¼25 (32)
Below average 4 (13) 4 (13) ––1 (4) 1 (4)
Average 19 (61) 13 (42) 8 (36) 5 (23) 4 (16) 6 (24)
Above average 4 (13) 8 (26) 7 (32) 7 (32) 9 (36) 12 (48)
High 2 (7) 2 (7) 5 (23) 6 (27) 11 (44) 5 (20)
Very high 2 (7) 4 (13) 2 (9) 4 (18) –1 (4)
Statistical analysis of the distribution of results between the test and control group in individual psychological tests. IQ: Intelligence Quotient.
a
Chi
2
¼3.125; p¼.537.
b
Chi
2
¼1.440; p¼.692.
c
Chi
2
¼4.079; p¼.395.
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The analysis of the Raven’s Progressive Matrices in
school age children, as in previous tests, also did not
show any differences in the distribution of intelligence
quotient between the study and control groups
(Chi
2
¼4.079; p¼.395). A detailed description of
results of conducted psychological tests on quotient of
intelligence in particular age groups are presented in
Table 3. The conducted tests have shown isolated
cases of significant intellectual development disturban-
ces as illustrated in Table 4.
Discussion
The evaluation of mental development, including intel-
ligence quotient testing, is an important element in
analyzing the development of infants and children. It
is believed that mental impairment is related to con-
genital, acquired, and inherited factors, which may
lead to permanent changes in the central nervous sys-
tem and cause difficulties in learning and adaptation.
Neurodevelopmental outcomes are strongly
dependent on gestational age at the time of delivery
[10–13]. According to available data and our experi-
ence, infants born to transplanted mothers have an
increased risk of prematurity, fetal growth restriction,
and low birth-weight compared with the general
population [4,14,15]. Results of published studies indi-
cate that more than 50% of this group of children,
who were additionally born before 30th week of ges-
tation, present moderate or severe cognitive disorders
in early school age [16,17]. These symptoms are similar
to infants born of pregnancies complicated by fetal
growth restriction [18]. Therefore, pregnancy in graft
transplant recipients combined with the influence of
immunosuppressive agents might result in negative
impact on neurological development of the fetus and
result in impairment of mental health of their children.
In our study group, the majority of newborn of liver
transplant mothers were delivered at term (64%) with
a birth-weight above 2500 g (81%). In children of
mothers after kidney transplantation, these values
were significantly lower (38% and 50%, respectively).
However, in spite of these differences, the analysis of
the distribution of test results on the quotient of intel-
ligence did not reveal any significant differences
between the two subgroups of children delivered by
post-transplant mothers. Most of the children in both
analyzed subgroups had an average score on the quo-
tient of intelligence.
Results less than 85 points are used internationally
to determine the degree of disability and to identify
the causes of poor learning and the need for educa-
tional support, while the score <70 points defines
intellectual disability and points the need for a special
education [17,19,20]. In our study, the level of intelli-
gence below average was found in 6% of the children
of the analyzed population. The lowest IQ score was
found in the group of the youngest children of moth-
ers after liver or kidney transplant, reaching 84 and 87,
respectively. In the analyzed population, one child
from the control group was diagnosed with mild men-
tal impairment and the result of the quotient of the
intelligence obtained in the test was 64. The other
children from the control group with below average
scores, received 83 or more points in the IQ test.
On one hand, it is observed that children with
chronic liver or kidney disease and those with solid
organ transplants have higher incidence of abnormal
mental development [21]. They suffer from intellectual
deficits and have lower academic achievements; how-
ever, no data on long-term follow-up are available
[22]. On the other hand, transplant surgery seems to
positively affect mental abilities in children with
chronic organ failure [23]. However, in the light of our
data, it seems that the mental development of chil-
dren born to mothers after liver or kidney transplants
is similar to that of children from the control group
matched according to the gestational age at time of
Table 4. Abnormalities diagnosed during psychological evaluation in the study and the control group.
Type of the test Diagnosed abnormalities KT, n¼36 LT, n¼42 Control group, n¼78
Psyche Cattell Infant Intelligence Scale Speech delay 4 2 2
Psychomotor hyperactivity 1 0 1
Terman-Merril Intelligence Scale Speech delay 1 4 4
Speech impediment –logopedic therapy 1 3 5
Psychomotor hyperactivity 4 1 2
Emotional inhibition 0 1 1
Impaired grapho-motor skills 0 0 1
Scales of Raven’s Progressive Matrices Speech impediment –logopedic therapy 0 1 9
Psychomotor hyperactivity 2 2 1
Delayed school readiness 0 1 1
Emotional disorders –low self-esteem 0 0 1
Disturbed relations with peers 0 1 4
KT: children of kidney transplant mothers; LT: children of liver transplant mothers.
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delivery. It also seems that prenatal exposure of
fetuses to immunosuppressive agents does not affect
their intellectual development after childbirth.
To the best of our knowledge, this study is the first
to evaluate the possible differences in the intellectual
development of children born to post-transplant
mothers. However, some of the study limitations must
be mentioned. First, the lack of significant differences
in results between groups may be due to a relatively
small study population. Second, the main criterion for
matching groups in our study was gestational age, but
other possible factors that might have an impact on
the intellectual development of the examined children
were not taken into account. However, the results of
our study indicate that there is no difference in the
distribution of IQ between the study and control
group. Hence, it can be concluded that, regardless of
possible differences in pregnancy, there are no differ-
ences in the intellectual development of children of
post-transplant mothers. Third, there are data indicat-
ing the effect of postnatal influences on cognitive
development such as parental or caregiver education,
social, or economic status, which in our study were
not factored in the analysis. This may be due to the
fact that presented study is a part of a wider analysis
than the children’s intellectual estimation. Fourth, each
test, including those used in to assess intellectual
development, has their own limitations. Nonetheless,
the selection of these tests was not accidental and
selected by psychologists according to the age of
participants.
In conclusion, we would like to emphasize that
results of our study appear to have clinical implica-
tions and enable counseling regarding possible preg-
nancy planning. Providing additional information on
the low risk of intellectual developmental disorders in
children of post-transplant mothers may influence on
women’s decision about maternity.
Acknowledgements
The authors would like to thank our colleagues from trans-
plant team who provided expertise in multidisciplinary care
of our post-transplant pregnant women.
Disclosure statement
The authors report no conflicts of interest.
Funding
This study was supported by the Polish Ministry of Science
and Higher Education Grant [No. N407 534938/10].
ORCID
Monika Szpotanska-Sikorska http://orcid.org/0000-0001-
9051-0319
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