Recent data shows that 30 million low-birth-weight (LBW) infants are born annually worldwide (23.8% of all births). Although the global prevalence of such births is gradually decreasing, rates are still as high as 30% in many developing countries (World Health Organization 2008). Low birth weight is due to intrauterine growth restriction (IUGR), rather than or in addition to prematurity, in approximately one-third of these cases. This staggering number of affected children underscores the importance of understanding the short- and long-term cognitive and behavioral complications of IUGR. Intrauterine growth restriction conveys short- and long-term neurodevelopmental risks and thus requires costly long-term investment of medical, cognitive emotional, educational, and economical resources. Nevertheless, if treated aggressively, IUGR more often than not bears a fairly optimistic outlook, once the infant overcomes the initial life-threatening issues (Geva et al. 2006a). Intrauterine growth restriction is frequently detected in a pregnancy with a less-than-expected third trimester weight gain (100–200 g [3.5–7 oz] per week) or as an incidental finding on ultrasound examination when fetal measurements are less than expected for gestational age (GA; Geva et al. 2005). An estimated fetal weight under the 10th percentile, as determined by serial ultrasound examination, strongly correlates with growth restriction (Bernstein and Gabbe 1996; McCormick 1985). The etiologies of IUGR are typically thought of according to three interdependent categories: fetal factors, placental factors, and maternal factors (Kay 2008). Fetal factors include chromosomal events, such as trisomy 18 and 13 and sex chromosome abnormalities, which account for 5%–15% of all IUGR cases. Further exploration of genetic factors is currently under way, with mixed results (Kotzot et al. 2001). Other fetal factors linked to IUGR include congenital anomalies, mostly cardiovascular malformations, gastroschisis and omphalocele; infection, often related to rubella, cytomegalovirus, and toxoplasmosis (see Chapter 25); and multiple gestations, in which uteroplacental blood flow variations and/or twin–twin transfusion develops (Miller et al. 2008). Fetal villus circulation abnormalities are placental factors related to IUGR (Roberts and Post 2008).
OP01.06: Short and long-term impact of intrauterine growth restriction on neurobehavior, white matter diffusion and connectivity in a rabbit model
