CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 2, March/April 2014
76
AFRICA
between children born as SGA and AGA. Our research showed
a higher frequency of high blood pressure values diagnosing
prehypertension or hypertension in SGA patients, which is
consistent with the reports of other investigators.
17-19
Incidentally our results correspond with reports of a
prospective multi-centre study of 950 American children, of
whom 28% were children with IUGR. The authors of that
study found that in a group of six-year-old children with IUGR,
hypertension occurred in 25% of them, whereas in only 16% of
the control group.
18
In that study, as in ours, the children were of
comparable ages (6–8 years), born at term, in whom IUGR was
determined based on a birth weight of less than the 5th
17
or 10th
percentile,
18
according to the centiles developed for the particular
population.
Since IUGR affects particularly developing countries, the
article by Law
et al
. is relevant. It was based on children 3–6
years old from China and North and South America (Guatemala
and Chile). The authors found a relationship between higher
blood pressure values and lower birth weight.
20
There are many
other studies in African countries where similar results were
observed.
21,22
In all of these studies, analysis was made on the
basis of average values from triple oscillometric measurements
of blood pressure.
In another large, retrospective study, the Collaborative
Perinatal Project, analysis of blood pressure in seven-year-old
children was based on a single measurement. In that population
of more than 2 600 children born with IUGR, the presence of
higher blood pressure values was not confirmed compared to
children born as eutrophic.
23
This method of blood pressure
assessment did not show significant differences. In our study, the
oscillometric method confirmed higher DBP but not SBP values.
It appears therefore that, especially in young children, 24-hour
ABPM during ordinary activity of the child is a much more
accurate assessment, as was done in our study. The only research
available to us that evaluated the association between birth weight
and blood pressure assessment using ABPM measurements was
in a group of 39 children with IUGR.
6
However, the conclusions
of Bilge
et al.
differed from ours despite similar methods and
a similar age of the study group, although fewer children were
included in the study. The authors did not observe a statistically
significant higher incidence of abnormal blood pressure values
among the IUGR children.
It has been proven that higher blood pressure values are not
only the result of low birth weight but also too rapid weight gain
within the first two years of life, which can lead to overweight
and obesity.
24
On the other hand, from studies in low- and
middle-income countries, it is known that in SGA children,
undernutrition exists not only in the intra-uterine period but also
during childhood.
1
This can imply serious health consequences in
later life, including higher risk of mortality.
1,25
In our research, there were no significant differences in body
weight, height and BMI at the time of the study between the SGA
and AGA children. Therefore intra-uterine growth retardation
was an independent risk factor for abnormal blood pressure in
childhood, and their nutritional status did not matter.
In this article, we also distinguished between children with
symmetrical and asymmetrical IUGR among the SGA group
on the basis of anthropometric measurements at birth, including
ponderal index. In children with asymmetrical IUGR, higher
daytime and 24-hour SBP as well as daytime MAP were found.
This may suggest that this subgroup is more prone to higher
blood pressure values in early childhood, due to normal growth
potential. However, the size of this subgroup was rather small
and this observation needs further investigation.
When isolating the subgroup of SGA children according to
birth weight (
≤
5th percentile and 5th–10th percentile), there
was no significant difference in the incidence of abnormal blood
pressure values. It appears that assessing intra-uterine growth
restriction only on the basis of birth weight does not reflect the
risk of developing hypertension. Some authors tried to find other
perinatal parameters describing body proportions that better
correlate with metabolic dysfunction and high blood pressure in
later life.
23
This encourages further investigation of the causes of
more frequent and earlier occurrence of hypertension in IUGR
children compared to healthy AGA children.
The major limitation of this work was the relatively small
group of patients. However, this was a single-centre study,
which could constitute the beginning of a wider research. We
intentionally used fewer subjects in the AGA group, so that
they could be comparable to the subgroups of SGA children
(asymmetrical and symmetrical).
Conclusion
In children born as SGA, abnormal blood pressure values
(prehypertension or hypertension) occurred more frequently than
in healthy children. This correlation did not provide a significant
relationship with the type of IUGR (symmetrical/asymmetrical)
or birth weight percentile (
<
5th percentile vs 5–10th percentile),
which could have been the result of the small number of patients.
It seems reasonable therefore that children born with IUGR
should remain under paediatric care. In cases of elevated blood
pressure values during standard medical examination or any
other risk factors of cardiovascular disease, these patients should
be directed to a more accurate assessment of blood pressure
values using APBM.
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