o_1977r8vv9vk1ts2ms0kd8pksa.pdf

170 D. Ley, K. MarsÏ—l
mals decreases IGF-I expression in many tissues and
in the circulation [76, 77]. Circulatory levels of IGF-I
have been shown to be decreased in SGA fetuses and
in fetuses with abnormal blood flow velocity [78, 79].
In our study at 18 years of age, the central field vision,
as represented by the Rarebit mean hit rate
[72], ranged from 93 to 100% in subjects with birthweight
AGA and from 48 to 100% in those with
birth-weight SGA with the median hit rate being significantly
lower in the SGA group as compared with
that in the AGA group (p=0.03). Eight of the SGA
subjects and none of the controls had a hit rate below
the normal range (p=0.006). The deviant hit rates
detected by the Rarebit microdot perimetry in some
SGA subjects may reflect defects in the matrix of detectors,
i.e., the neural channels, and may be caused
by disturbed axonal growth or development. This
finding of abnormal function lends support to the
previously mentioned morphological finding of reduced
neuroretinal rim area in subjects with IUGR.
Fetal Aortic Blood Flow and Postnatal
Cardiovascular Function
Aortic Vessel Wall Characteristics
and Blood Pressure at 9 Years of Age
We used an electronic phase-locked echo-tracking
system DIAMOVE (Teltec, Lund, Sweden) for non-invasive
monitoring of pulsatile diameter changes in
the descending aorta [81, 82] of a subgroup of 68
children from the original Malmæ cohort. Neither abnormal
fetal aortic blood flow nor birth-weight deviation
were reflected in any significant changes in elastic
modulus or stiffness of the abdominal aorta at 9
years of age [80]. Within the examined group, the
subjects with the highest body weight at the time of
examination had the highest levels of systolic blood
pressure. These results support the hypothesis that
the link between fetal growth failure and high blood
pressure in adult life may mainly be expressed among
those with obesity.
Children born SGA had significantly lower vessel
diameters than those born AGA and these differences
remained significant after adjustment for body surface
area. These findings resemble in part those of
Stale et al. [83] who found lower values of end-diastolic
diameters in SGA fetuses than in AGA fetuses
of the same gestational age using an identical technique
for aortic measurements; however, when the fetal
aortic diameters were adjusted for estimated fetal
weight, the relationship was reversed. The larger
weight-related diastolic diameter taken together with
the finding of a lower relative pulse amplitude in the
SGA fetuses suggested an increase in diastolic blood
pressure, possibly as a response to the increased peripheral
resistance, namely that of the placental circulation,
found in pregnancies complicated by IUGR.
The present findings obtained at 9 years of age [80]
showed no evidence of an increase in diastolic blood
pressure related to restricted fetal growth. On the
contrary, IUGR was associated with lower diastolic
blood pressure. As the influence of the increased resistance
to fetal blood flow caused by the abnormal
placenta in fetal growth restriction will cease to exist
after birth, it would seem plausible that the postulated
compensatory increase in blood pressure during
the fetal period would no longer be present in childhood.
Pulse pressure was significantly higher within the
group of children born SGA than in those born AGA
[80]. An increase in pulse pressure has previously
been described in SGA infants at 6 weeks of age [84]
and has been associated with signs of low arterial
compliance and hypertensive disease in adults [85,
86]; however, we were unable to detect any corresponding
changes in aortic compliance in association
with either abnormal fetal aortic blood flow or SGA
birth weight. A previous study of human aortic compliance
and its normal variation with age found a
profound increase in compliance between 4 and 11
years of age [87]. Aortic compliance thereafter exhibited
a gradual decrease with values beyond 16 years
being similar to those of healthy adults. This may imply
that changes in aortic vessel compliance due to
fetal causes may be detectable at a later age when
aortic compliance decreases due to the normal ageing
process. The increase in pulse pressure observed in
the SGA group [80] might suggest, in the absence of
changes in elastic modulus and stiffness of the
abdominal aorta, the possibility of corresponding
changes in more peripheral segments of the arterial
tree.
Size and Function of Large Arteries
at 18 Years of Age
At 18 years of age [88], vascular mechanical properties
of the common carotid artery (CCA), abdominal
aorta (AO), and popliteal artery (PA) were assessed
by echo-tracking sonography in 21 adolescents with
IUGR and abnormal fetal aortic blood flow, and in 23
adolescents with normal fetal growth and normal
fetal aortic blood flow, all belonging to the Malmæ-
Lund follow-up cohort [71±73, 89]. Endothelium-dependent
and endothelium-independent vasodilatation
of the brachial artery was measured by high-resolution
ultrasound.
The IUGR group had significantly smaller mean
vessel diameters compared with controls in the AO
and PA in proportion to the body size, with a similar
trend in the CCA. Stiffness in all three vascular re-