Final answer:
Maternal undernutrition can lead to low birthweight through intrauterine growth restriction (IUGR), while placental insufficiency restricts nutrient and oxygen transfer to the fetus. Teratogen exposure, such as alcohol and smoking, can result in developmental disorders and growth weakness. Additionally, infections like rubella can cause severe birth defects.
Step-by-step explanation:
Maternal factors that can lead to an infant being small for gestational age (SGA) include various conditions and exposures during pregnancy that affect fetal growth. One significant factor is undernutrition, which can cause intrauterine growth restriction (IUGR) due to insufficient nutrients reaching the fetus. This can result in low birthweight babies who are more at risk for disease and developmental issues. Another concern is placental insufficiency, a condition where the placenta fails to deliver enough oxygen and nutrients to the fetus, contributing to IUGR.
Additionally, exposure to teratogens such as alcohol and smoking during pregnancy can have severe consequences. Fetal alcohol spectrum disorder, resulting from alcohol consumption, can cause cognitive deficits, developmental delays, and characteristic facial abnormalities. Smoking can lead to growth weakness and may result in various adverse outcomes due to carbon monoxide and other harmful substances in cigarettes competing with oxygen binding in the blood. Lastly, infections like rubella during pregnancy can cause an array of birth defects, impacting the developing fetus significantly.