ABSTRACT
Fetal Factors Multiple fetal factors affect growth. Between 4% and 25% of fetuses with growth restriction will have an abnormal karyotype (35,36). Trisomy 18 is particularly at risk for FGR as 35% of these fetuses will measure <10th percentile (37). Other chromosomal anomalies, particularly trisomies, triploidy, translocations, and sex chromosome abnormalities are also at high risk for FGR. Other than chromosomal aberrations, genetic disorders such as uniparental disomy and imprinting disorders are rare causes of FGR (34). Many genetic disorders can lead to major structural malformations, and the findings of these on ultrasound will increase the risk of growth abnormalities to 22% (38). Fetal infection has been associated with FGR, but data on the exact incidence of fetal infection in FGR are scant. Known infections that have been associated include cytomegalovirus, varicella, herpes simplex virus, malaria, human immunodeficiency virus, rubella, and syphilis (1). Malaria is the most common cause of FGR worldwide.
