Final answer:
Uteroplacental issues such as placental insufficiency can cause inadequate transfer of nutrients and oxygen to the fetus, leading to intrauterine growth restriction and resulting in an infant that is SGA with increased risks for health issues.
Step-by-step explanation:
Uteroplacental issues can lead to an infant that is small for gestational age (SGA) mainly due to a condition known as placental insufficiency. This is a problem with the placenta that results in inadequate transfer of oxygen and nutrients to the fetus, causing intrauterine growth restriction (IUGR). IUGR refers to abnormally slow growth of a fetus, which can result from various maternal, fetal, or placental factors.
When the placenta does not function properly, it can lead to undernutrition and low birthweight in newborns. A low birth weight, defined as less than 2.5 kg (5.5 lb), can increase the risk of disease and infant mortality, and may result in developmental delays and slow growth in early childhood.
The fetal heart and blood vessels develop early on, and fetal hemoglobin, which is different from adult hemoglobin, allows the fetus to receive oxygen from the mother's blood via the placenta efficiently. However, if the placenta fails to provide the necessary nutrients and oxygen due to insufficiency, the fetus may be unable to reach a normal weight before birth. Birth weight is crucial as it is a major indicator of a newborn's initial health status and future developmental outcomes.