Substance Abuse & Fetal Circulation
Fetal Circulation Overview: Substances used during pregnancy can cross the placenta and interfere with fetal
circulation by causing vasoconstriction, damaging the placenta, or lowering oxygen availability. These
disruptions reduce oxygen and nutrient delivery to the fetus, leading to growth restriction, fetal hypoxia,
preterm birth, and developmental problems.
Tobacco
Restricts placental blood flow through vasoconstriction, reducing the oxygen available to the fetus. Carbon
monoxide binds to fetal hemoglobin, lowering its oxygen-carrying capacity. Even if the mother eats well,
babies exposed to tobacco often have low birth weight (LBW) due to impaired nutrient and oxygen delivery.
Smoking also affects nutrient absorption, making prenatal vitamins less effective. Fetal Circulation Effect:
Chronic hypoxia, IUGR, and increased risk of stillbirth, SIDS, and delayed development.
Cocaine
Activates the sympathetic nervous system, increasing maternal heart rate and blood pressure. This causes
intense vasoconstriction, sharply reducing oxygen and nutrient flow to the fetus. Cocaine can also trigger
placental abruption, preterm labor, and fetal heart irregularities. Fetal Circulation Effect: Fetal hypoxia,
IUGR, LBW, stillbirth, stroke, NAS, and cardiovascular stress.
Alcohol
Crosses the placenta freely and stays in fetal tissues longer due to immature liver enzymes. It damages the
fetal vascular system, impairs oxygen supply, and reduces ATP (energy) production. Alcohol also impairs
placental circulation, reducing nutrient transfer. Fetal Circulation Effect: Brain oxygen deprivation leads to
FASD, microcephaly, growth restriction, and heart defects.
Caffeine
Blocks adenosine receptors and stimulates catecholamines, which can cause vasoconstriction of placental
vessels. This limits blood flow to the fetus and may raise fetal heart rate. In large amounts, caffeine
increases the risk of miscarriage and low birth weight. Fetal Circulation Effect: Mild reduction in placental
perfusion may lead to IUGR, preterm delivery, and fetal stress.
Opioids and Methadone
Cross the placenta and suppress fetal breathing and movement, both signs of reduced oxygenation. Opioids can
impair placental perfusion and fetal circulation. Maternal withdrawal causes intermittent hypoxia, which can
harm fetal development. Fetal Circulation Effect: Decreased oxygen delivery can result in fetal distress, NAS,
SIDS, and poor neurodevelopment.
This study source was downloaded by 100000898062787 from CourseHero.com on 09-30-2025 01:58:26 GMT -05:00
https://www.coursehero.com/file/251675843/Substance-Abuse-and-Fetal-Circulationpdf/
Fetal Circulation Overview: Substances used during pregnancy can cross the placenta and interfere with fetal
circulation by causing vasoconstriction, damaging the placenta, or lowering oxygen availability. These
disruptions reduce oxygen and nutrient delivery to the fetus, leading to growth restriction, fetal hypoxia,
preterm birth, and developmental problems.
Tobacco
Restricts placental blood flow through vasoconstriction, reducing the oxygen available to the fetus. Carbon
monoxide binds to fetal hemoglobin, lowering its oxygen-carrying capacity. Even if the mother eats well,
babies exposed to tobacco often have low birth weight (LBW) due to impaired nutrient and oxygen delivery.
Smoking also affects nutrient absorption, making prenatal vitamins less effective. Fetal Circulation Effect:
Chronic hypoxia, IUGR, and increased risk of stillbirth, SIDS, and delayed development.
Cocaine
Activates the sympathetic nervous system, increasing maternal heart rate and blood pressure. This causes
intense vasoconstriction, sharply reducing oxygen and nutrient flow to the fetus. Cocaine can also trigger
placental abruption, preterm labor, and fetal heart irregularities. Fetal Circulation Effect: Fetal hypoxia,
IUGR, LBW, stillbirth, stroke, NAS, and cardiovascular stress.
Alcohol
Crosses the placenta freely and stays in fetal tissues longer due to immature liver enzymes. It damages the
fetal vascular system, impairs oxygen supply, and reduces ATP (energy) production. Alcohol also impairs
placental circulation, reducing nutrient transfer. Fetal Circulation Effect: Brain oxygen deprivation leads to
FASD, microcephaly, growth restriction, and heart defects.
Caffeine
Blocks adenosine receptors and stimulates catecholamines, which can cause vasoconstriction of placental
vessels. This limits blood flow to the fetus and may raise fetal heart rate. In large amounts, caffeine
increases the risk of miscarriage and low birth weight. Fetal Circulation Effect: Mild reduction in placental
perfusion may lead to IUGR, preterm delivery, and fetal stress.
Opioids and Methadone
Cross the placenta and suppress fetal breathing and movement, both signs of reduced oxygenation. Opioids can
impair placental perfusion and fetal circulation. Maternal withdrawal causes intermittent hypoxia, which can
harm fetal development. Fetal Circulation Effect: Decreased oxygen delivery can result in fetal distress, NAS,
SIDS, and poor neurodevelopment.
This study source was downloaded by 100000898062787 from CourseHero.com on 09-30-2025 01:58:26 GMT -05:00
https://www.coursehero.com/file/251675843/Substance-Abuse-and-Fetal-Circulationpdf/
