Compared to the general population, the incidence of congenital anomalies in infants exposed to heroin is:

• A. Decreased
• B. Increased
• C. Uncertain
• D. Not known

Answer: (C)

The main concept is that assessing teratogenic risk for a substance during pregnancy can be hampered by many confounding factors, and for heroin the data on congenital anomalies are not clear-cut. While heroin exposure in utero is clearly linked to neonatal withdrawal, low birth weight, and prematurity, studies looking at birth defects show mixed results. Some investigations hint at possible increases in certain anomalies, but others do not find a consistent pattern. This inconsistency is largely due to confounding factors common in this population—polysubstance use (tobacco, alcohol, other drugs), infections, poor prenatal care, nutrition, socioeconomic factors—and the challenges of accurately measuring and attributing exposure. Additionally, biases in reporting and small or selective study samples limit certainty about any real increase or specific defects. Because the evidence does not consistently demonstrate a definite rise (or fall) in congenital anomalies across populations and defect types, the safest, evidence-based stance is that the incidence is uncertain.