CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 2, March/April 2014
74
AFRICA
term as SGA (birth weight
<
10th percentile for gestational age),
which included 23 boys and 27 girls. In the SGA group there
were two subgroups: symmetrical (
n
=
20) and asymmetrical
IUGR (
n
=
30). SGA children were also divided into subgroups
according to birth weight percentiles:
≤
5th percentile (
n
=
23)
and between the 5th and 10th percentile (
n
=
27).
The control group consisted of 25 healthy volunteers born as
AGA, and matched for gender (13 boys and 12 girls) and age
with the study group (Table 1). Informed written consent was
obtained from all the parents, and the study was approved by the
research ethics committee.
A perinatal history was taken of all the children including
delivery, gestational age, weight, birth length, head circumference
and ponderal index.
3
Somatic parameters applied to the centiles
were developed for the Polish population.
11
Risk factors for IUGR were determined in both groups,
including environmental factors: smoking, alcohol intake during
pregnancy; maternal factors: hypertension, diabetes, infection
during pregnancy; and placental factors: structural and functional
anomalies of the placenta.
A family history of cardiovascular disease was taken,
including the occurrence of hypertension. The nutritional status
of all the children was assessed from their height, weight and
body mass index [BMI
=
weight/height
2
(kg/m
2
)] by centiles
developed for the Polish population.
12
Echocardiography (Aloka Prosound Alpha 10) was done to
evaluate cardiac structure and function. Left ventricular mass
(LV mass) was measured in the parasternal short- and long-
axis view, in M-mode projection. Two formulae were used to
calculate LV mass: the Deveroux index (LV mass/body surface
area), which is automatically calculated by the device, and de
Simone index (LV mass/height
2.7
). Measurements was taken
according to the American Society of Echocardiography.
13
Triple oscillometric measurements of blood pressure, using
a sphygmomanometer with an appropriate cuff adapted to the
length and circumference of the patient’s arm, were taken in a
controlled environment after at least five minutes of rest in a
seated position. Children over seven years of age were assessed
according to the centiles developed in the OLAF study,
14
and
younger children were assessed according to the Fourth Report
of the the Working Group on High Blood Pressure in Children
and Adolescents.
15
Ambulatory blood pressure monitoring (ABPM) was done
during the normal activity of the child, using a recorder (Tracker
Reynolds NIBP 2) combined with an appropriate-sized cuff
placed on the non-dominant hand. Based on the analysis of
measurements made every 20 minutes during the day and every
30 minutes during the night, the following were obtained: (1)
mean systolic blood pressure (mean SBP): average values for
the entire 24-hour period, (2) mean diastolic blood pressure
(mean DBP): average values for the entire 24-hour period, (3)
mean arterial pressure [MAP
=
(2
×
DBP
+
SBP)/3] during the
24-hour period, (4) SBP load for the 24-hour period (defined
as the percentage of valid ambulatory SBP measures above the
95th percentile of SBP for age, gender and height), (5) DBP
load for the 24-hour period (defined as the percentage of valid
ambulatory DBP measures above the 95th percentile of DBP for
age, gender and height).
According to recommendations developed by Urbina
et al
.,
16
the following were determined: normal blood pressure (SBP
of 24-hour period
<
95th percentile and SBP load
<
25%),
prehypertension (SBP of 24-hour period
<
95th percentile and
SBP load 25–50%), or hypertension (SBP of 24-hour period
>
95th percentile and SBP load
≥
25%).
Statistical analysis
Descriptive statistics were executed by computing the mean
and standard deviation (SD) for scale variables, or frequencies
for nominal variables. The significance level was computed
for the differences between variables in the AGA and SGA
groups. To evaluate the differences between the two groups, a
parametric
t
-test and a non-parametric Mann-Whitney test were
performed. The normality of scale variables was assessed using
the Kolmogorov-Smirnov test. All tests were two sided and
performed at the
p
<
0.05 level.
Pearson and Spearman correlation coefficients were computed
to evaluate the degree of association between variables either for
the control or study group. Statistical analysis was performed
using Statistica 10 software (StatSoft Inc., Tulsa, USA) and a
dedicated author’s software based on Microsoft SQL Server
2008 database management system.
Results
There were no statistically significant differences between the
groups in the distributions of gender, age and anthropometric
parameters (weight, height, BMI) at the time of the study.
Likewise, except for body measurements (birth weight, length and
head circumference), Apgar score, and other perinatal parameters
(gestational and maternal age) did not differ statistically
significantly (Table 1). There was a significant difference in
PI between the symmetrical (mean 2.02
±
0.26 g/cm
3
) and
asymmetrical (mean 1.75
±
0.16 g/cm
3
) subgroups (
p
<
0.01).
Among the children in the SGA group, the occurrence of
one or more risk factors for IUGR was observed significantly
more often, regardless of the type of IUGR (
r
=
0.42,
p
<
0.01).
An analysis was performed on the prevalence of risk factors
of IUGR in children in the AGA and SGA groups, with an
additional division into symmetrical and asymmetrical type.
Table 1. Characteristics of the groups.
Parameters
AGA group
(
n
=
25)
SGA group
(
n
=
50)
p-value
x
SD
x
SD
Current weight (kg)
26.96 8.59 25.41 9.32 NS
Current height (cm)
128.36 10.46 125.01 9.79 NS
Current BMI (kg/m
2
)
16.15 2.7 15.88 3.21 NS
Birth weight (g)
3409.2 489.75 2564.3 184.97
<
0.001
Birth length (cm)
54.76 3.37 51.84 2.52
<
0.001
Head circumference (cm)
34.28 1.43 32.97 1.35
<
0.001
Apgar score
9.48 0.77 8.66 0.89
<
0.001
Ponderal index (g/cm
3
)
2.08 0.27 1.86 0.24
<
0.001
Maternal age (years)
28.6 4.5 26.9 5.4 NS
Gestational age (weeks)
39.1 0.78 39.1 0.94 NS
SGA: small for gestational age; AGA: appropriate for gestational age;
ponderal index [PI
=
birth weight (g)
×
100/ birth length
3
(cm
3
)]; BMI
(body mass index)
=
weight (kg)/height
2
(m
2
);
p
-value: statistical signifi-
cance; NS: not significant.
