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Intrauterine growth restriction (IUGR) is a syndrome characterized
by a severe deficiency of foetal growth compared to the normal standards
for the gestational age. A definition and classification of IUGR,
shared among different countries, has not been yet agreed. For this
reason, it is difficult to be confident about the frequency of the
disease. However, an accepted figure is that approximately 7% of
pregnancies are complicated by IUGR. Although it is less common
compared to spontaneous abortion and malformative syndromes (some
of which due to chromosome abnormalities), this condition is considered
a severe disease since it can lead to adverse outcomes during pregnancy
(foetal death or pre-eclampsia) (1), during labour (complicated
delivery, premature birth, perinatal stress) (2,3) and the neonatal
period (respiratory distress syndrome, cerebral vascular damage)
(4-8). IUGR has an important impact on social and medical care because
it is associated to perinatal morbidity and mortality and to an
increased risk of learning delay during infancy. In addition, some
studies have reported a correlation among low birth weight and cardiovascular
and metabolic diseases during adult life (9,10,11).
Foetal growth
restriction is defined as a reduction from the physiological growth
rate, and it is usually due to foetal malnutrition. The diagnosis
is based on multiple ultrasound records evidencing an abdominal
circumference < 10th centile
or a reduction of growth during the second half of pregnancy (12,13).
This definition provides a tool to distinguish IUGR from SGA-(small
for gestational age) babies; nevertheless, the correct definition
and classification criteria of IUGR are still a challenge. IUGR
is primarily determined by a restriction of foetal rate of growth
during pregnancy, and a low birth weight does not always imply an
IUGR condition. At present, no therapies for foetuses showing an
abnormal rate of growth are available and the correct timing of
delivery remains the best medical approach for this condition.
The abdominal
circumference reduction is the most important distinguishing characteristic
of this disease (12,13). Early during pregnancy a foetus, which
is receiving nutrients at a low rate, acts to protect the brain
(the so-called brain-sparing effect) by reducing the supply of blood
to the abdominal organs. The subsequent result of such prolonged
compensation is that nutrient delivery becomes insufficient
to ensure normal foetal growth, leading to abdominal growth restriction
(14-18). In the last stage of the disease, oxygen supply becomes
insufficient leading to failure and consequent permanent damage
to the foetal brain (19).
The identification
of causes related to this condition is of paramount importance in
the development of strategies for the prevention and treatment of
the disease.
1. Ysak M.,
Lorentz RP., Kisly A. (1995) Pregnancy outcome in nulliparous women
35 years and older. Obstet Gynecol, 85 (1): 65-70.
2. Visser G.H., Sadovsky G., Nicolaides K.H. (1990) Antepartum heart
rate patterns in small for gestational age third-trimester fetuses:
Correlations with blood gas values obtained at cordocentesis. Am
J Obstet Gynecol, 162 : 698-703.
3. Berkowitz G.S., Skovron M.L., Lapinski R.H., Berkowitz R.L. (1990)
Delayed childbearing and the outcome of pregnancy. N Engl J Med,
322 (10): 693-694.
4. Bernstein I.M., Horbar J.D., Badger G.J., Ohlsson A., Golan A.
(2000) Morbidity and mortality among very-low-birth-weight neonates
with intrauterine growth restriction. Am J Obstet Gynecol, 182:
198-206.
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retardation at term. Br J Obstet Gynaecol, 100: 1076-1081.
6. Villar J., De Onis M., Kestler E., Bolanos F., Cerezo R., Bernedes
H., (1990) The differential neonatal morbidity of the intrauterine
growth retardation syndrome. Am J Obstet Gynecol, 163: 151-157.
7. Gortner L., Wauer R.R., Stock G.J., Reiter H.L., Reiss I., Jorch
G., Hentschel R., Hieronimi G. (1999) Neonatal outcome in small
for gestational age infants: do they really
do better? J Perinatal Medicine, 27 (6) : 484-489.
8. Holtrop
P.C. (1993) The frequency of hypoglycemia in full-term large and
small for gestational age newborns. American Journal of Perinatology,
10 (2) : 150-154.
9. Allan W.C., Riviello J.J. (1992) Perinatal cerebrovascular disease
in the neonate: parenchimal ischemic lesions in term and preterm
infants. Ped Clin N Amer, 39: 621.
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301 (6761): 1111.
11. Barker D.J. (1993) The intrauterine origins of cardiovascular
disease. Acta Pediatr Suppl , 82 Suppl 391: 93-99.
12. Ferrazzi E., Todros T., Groli C., Nicolini U., Parodi L., Pavoni
M., Zorzoli A., Zucca S. (1987) Fitting growth curves to head and
abdomen measurements of the fetus: a multicentric study. J Clin
Ultrasound, 15 (2) : 95-105.
13. Nicolini U., Ferrazzi E., Molla R., Massa E., Cicognani G.,
Santarone M., Bellotti M., Pardi G. (1986) Accuracy of an average
ultrasonic laboratory in measurements of fetal biparietal diameter,
head circumference and abdominal circumference. J Perinat Med, 14:
101.
14. Pardi G., Cetin I., Marconi A.M., Lanfranchi A., Bozzetti P.,
Ferrazzi E., Buscaglia F.C., Battaglia F.C. (1993) Diagnostic value
of blood sampling in fetuses with growth retardation. New Engl J
Med, 328: 692-696.
15. Giles W.B., Trudinger B.J., Baird P.J. (1985) Fetal umbilical
artery flow velocity waveforms and placental resistance: pathological
correlation. Br J Obstet Gynaecol, 92: 31-38.
16. Ferrazzi E., Vegni C., Bellotti M., Borboni A., della Peruta
S., Barbera A. (1991) Role of umbilical Doppler velocimetry in the
biophysical assessment of the growth retarded fetus. Answers from
neonatal morbidity and mortality. J Ultrasound Med, 10 (6): 309-315.
17. Gosling R.G., King D.H. (1974) Continuous wave ultrasound as
an alternative and complement to X-rays in vascular examination.
In: Reneman r.s., ed Cardiovascular applications of ultrasound.
Amsterdam: North Holland, 266-282.
18. Ott WJ. Intrauterine growth restriction and Doppler ultrasonography.
J Ultrasound Med 2000; 19: 661-665.
19. Pardi
G., Marconi A.M, Cetin I. (2002) Placental-fetal Interrelationship
in IUGR Fetuses-A Review. Trophoblast Research, 2002, 23: S136-S141
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