INTRODUCTION: Intrauterine growth restriction (IUGR) is a common diagnosis in obstetrics that is refers to the fetus with a birth-weight at or below the 10th percentile for gestational age and sex, with an increased risk of perinatal mortality and morbidity. Identification of IUGR is essential because proper assessment and management can result in a hopeful outcome. Growth restriction is classified as symmetric and asymmetric and the etiology has been differentiated according to maternal, placental and fetal factors. However, Accurate dating early in pregnancy is essential for a diagnosis of IUGR.
Furthermore, Ultrasound biometry is the gold standard for assessment of fetal size and the amount of amniotic fluid, while Serial ultra-sonograms are important for monitoring growth restriction, therefore; the first step in the management of fetuses with IUGR is to detect pregnancies affected by any serious complication. In General, management measures include treatment of maternal disease, good nutrition and bed rest. While Preterm delivery is indicated if the fetus shows evidence of abnormal function on biophysical profile testing. The fetus should be monitored continuously during labor to minimize fetal hypoxia (Peleg et al, 1998). The effects of prematurity affect the outcome of IUGR infants.
IUGR is associated with cerebral palsy in those delivered more than 32 weeks gestation. While infants less than 32 weeks of gestation may have poor developmental outcome if the head growth is affected, as well as cognitive and behavioral problems (Fang, 2005). In spite of many studies dealing with different aspects of IUGR in human pregnancies the pathphysiological processes underlying this disorder are complex and incompletely understood. So, different animal models were used to clarify processes regulating fetal growth in normal development and IUGR (Ergaz et al, 2005). Definition: Many terms have been used to describe fetus with small growth.
Those include “small for gestational age”, “intrauterine growth retardation”, “intrauterine growth restriction” and “small for date”. IUGR refers to a condition in which a fetus is unable to achieve its genetically determined potential size as estimated fetal weight at or below the 10th percentile for gestational age. This definition excludes fetuses that are small for gestational age (SGA) but are not pathologically small. Not all fetuses that are SGA are pathologically growth restricted (Harper et al, 2005). Asymmetric vs.
Symmetric growth restriction: IUGR is usually classified as symmetric and asymmetric. Symmetric growth restriction refers to a fetus whose entire body is proportionally small. While asymmetric growth restriction refers to a fetus that is undernourished with use of most of its energy to maintaining growth of vital organs, such as the brain and heart, and this type of growth restriction is usually the result of placental insufficiency (Peleg et al, 1998) as shown in table 1. Symmetric IUGRAsymmetric IUGRIncidence20%-30%70%-80%Period of growth restrictionBegins first or second trimesterBegins third trimesterPhysical characteristicsSmall head and abdominal sizeLarge head size relative to small abdomenPathopsychiologyImpaired cellular embryonic division. Impaired cellular hyperplasia ± hypertrophyDecreased cell number ± sizeImpaired cellular hypertrophyDecreased cell sizeEtiologyMostly intrinsic: chromosomal abnormalities and congenital malformationsDrugsInfectionEarly-onset severe preeclampsiaPreeclampsia < 30 wk superimposed with chronic hypertensionMostly extrinsic: placental and maternal vascular factors (e. g.
placental insufficiency)OutcomeGreater morbidity and mortalityLower morbidity and mortalityTable 1. Specific Distinctions Between Symmetric and Asymmetric Intrauterine Growth Restriction (IUGR) (Brodosky & Christou, 2004)Incidence: About 3-7% of all pregnancies are associated with IUGR and 20% of stillborn are IUGR.
However, mortality is 3-10 times higher for IUGR neonates than neonates of the same gestational age. Furthermore, of all IUGR neonates, incidence of Symmetrical IUGR, is 25%, while asymmetrical IUGR 75% Of all fetuses at or below the 10th percentile for growth, approximately 40% are at high risk of potentially preventable perinatal death (see figure 1) ( Harper et al, 2005 ). Therefore, inaccurately dated pregnancies, approximately 80-85 % of fetus identified as being SGA are constitutionally small but healthy, 10-15% are true IUGR cases (Sheridan, 2005).