Which class of medications should be avoided during the third trimester of pregnancy due to the risk of premature closure of the fetal ductus arteriosus?
Solution
Correct Answer: Option B
The correct answer is Nonsteroidal anti-inflammatory drugs (NSAIDs).
- During the third trimester of pregnancy, the use of NSAIDs is contraindicated primarily due to the risk of premature closure of the fetal ductus arteriosus.
- The ductus arteriosus is a vital fetal blood vessel that connects the pulmonary artery to the aorta, allowing blood to bypass the non-functioning fetal lungs.
- This vessel remains open (patent) largely because of the presence of prostaglandins.
- NSAIDs inhibit cyclooxygenase (COX) enzymes, leading to decreased synthesis of prostaglandins.
- Reduced prostaglandin levels can cause the ductus arteriosus to close prematurely in utero.
- Premature closure results in increased right ventricular pressure, right heart failure, pulmonary hypertension, and can lead to fetal demise or significant neonatal complications.
Other medication classes listed have different safety profiles:
- Angiotensin-converting enzyme inhibitors (ACE inhibitors) are contraindicated in the second and third trimesters due to fetal renal toxicity, oligohydramnios, and growth restriction but are not primarily linked to ductus arteriosus closure.
- Beta-blockers may carry risks such as fetal growth restriction or neonatal bradycardia but do not cause ductal closure.
- Calcium channel blockers are generally considered safe in pregnancy and are sometimes used to treat preterm labor.
Therefore, NSAIDs must be avoided especially in the third trimester to prevent the serious complication of premature ductus arteriosus closure.
Reference: Williams Obstetrics, 25th Edition, Chapter 44 – Drugs and Environmental Agents Affecting the Fetus and Newborn
- During the third trimester of pregnancy, the use of NSAIDs is contraindicated primarily due to the risk of premature closure of the fetal ductus arteriosus.
- The ductus arteriosus is a vital fetal blood vessel that connects the pulmonary artery to the aorta, allowing blood to bypass the non-functioning fetal lungs.
- This vessel remains open (patent) largely because of the presence of prostaglandins.
- NSAIDs inhibit cyclooxygenase (COX) enzymes, leading to decreased synthesis of prostaglandins.
- Reduced prostaglandin levels can cause the ductus arteriosus to close prematurely in utero.
- Premature closure results in increased right ventricular pressure, right heart failure, pulmonary hypertension, and can lead to fetal demise or significant neonatal complications.
Other medication classes listed have different safety profiles:
- Angiotensin-converting enzyme inhibitors (ACE inhibitors) are contraindicated in the second and third trimesters due to fetal renal toxicity, oligohydramnios, and growth restriction but are not primarily linked to ductus arteriosus closure.
- Beta-blockers may carry risks such as fetal growth restriction or neonatal bradycardia but do not cause ductal closure.
- Calcium channel blockers are generally considered safe in pregnancy and are sometimes used to treat preterm labor.
Therefore, NSAIDs must be avoided especially in the third trimester to prevent the serious complication of premature ductus arteriosus closure.
Reference: Williams Obstetrics, 25th Edition, Chapter 44 – Drugs and Environmental Agents Affecting the Fetus and Newborn
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