Fetal growth restriction
Fetal growth restriction (FGR) is the pathologic growth restriction of a baby resulting in a weight below the 10th percentile for its gestational age . The statistical measure of fetal growth restriction is gestational age specific, with some variability (and therefore inaccuracy) in the measured variable.
There are two types of fetal growth restriction: Symmetric (aka Type 1), which accounts for 20-30% of cases and is usually caused by infection or chromosome issues; and asymmetric (aka Type 2), which can be caused by uteroplacental insufficiency, and is responsible for 70-80% of cases.
Constitutional factors are responsible for 70-85% of the variability in low birth weight, extrinsic intrauterine growth restriction (IUGR) are responsible for 10-15%, and intrinsic intrauterine growth restriction (IUGR) is responsible for 5-10%.
Fetal factors are most commonly genetic, (5-20% of cases), though multiple gestations may become increasingly responsible in the future. Placental factors include previa, abruption, and other structural abnormalities. Maternal factors usually revolve around uteroplacental perfusion (25-30% of cases), usually under the impact of diseases such as diabetes or bad nutrition.