INTRAUTERINE GROWTH RESTRICTION (IUGR)

• Perinates with a weight at or below the 10th percentile for gestational age and sex. The problem with this definition is that it is similar to the small for gestational age fetus (SGA) (1-3). However IUGR implies a pathologic process, which affects normal fetal growth.
• Due to a pathologic process that inhibits the normal intrinsic growth potential.
• May be due to maternal, fetal or placental disorders alone or in combination.

SMALL FOR GESTATIONAL AGE (SGA)

• Pathologic term describing perinates with a weight at or below the 10th percentile for gestational age and sex without reference to the etiology.

THREE MAIN GROUPS:

Normally small fetus (80-95%)	Intrinsically abnormally small fetus (10-15%)	Dysmature small fetus (10-15%)
* No restraint of growth potential. * Weight <10th centile due to lower growth potential. * Asphyxia risk no greater than an appropriate age fetus. * Small/symmetrical. * Normal amniotic & fat distribution. * Intervention not indicated.	* Growth restriction due to a genetic/structural anomaly or infection. * May be severely IUGR. * Perinatal outcome related to defect rather than size. * Perinatal mortality high * Symmetric IUGR + normal or increased amniotic fluid. * Intervention rarely improves outcome.	* Extrinsic restriction of normal growth potential * Compromised placental function. * Asphyxial complications common and careful surveillance required. * Perinatal mortality high. * Asymmetric growth failure. * Oligohydramnios. * Abnormal biophysical profile. * Intervention can improve outcome.

REFERENCES

1. Ott WJ. The diagnosis of altered fetal growth. Obstet Gynecol Clin North Am 1988;15:237.
2. Ott WJ. Defining altered fetal growth by by second trimester Sonography. Obstet Gynecol 1990;75:1053.
3. Ott WJ. Intrauterine growth restriction and doppler ultrasonography. J Ultrasound Med 2000;19:661-665,