Maternity Nursing Q 153
Smoking is contraindicated in pregnancy because:
A. Nicotine causes vasodilation of the mother’s blood vessels.
B. Carbon monoxide binds with the hemoglobin of the mother reducing available hemoglobin for the fetus.
C. The smoke will make the fetus, and the mother feels dizzy.
D. Nicotine will cause vasoconstriction of the fetal blood vessels.
Correct Answer: B. Carbon monoxide binds with the hemoglobin of the mother reducing available hemoglobin for the fetus.
Carbon monoxide is one of the substances found in cigarette smoke. This substance diminishes the ability of the hemoglobin to bind with oxygen thus reducing the amount of oxygenated blood reaching the fetus.
Option A: There is blood flow restriction to the placenta due to the vasoconstrictive effects of catecholamines released from the adrenals and nerve cells after nicotine activation.
Option C: Nicotine is rapidly absorbed when the tobacco smoke reaches the small airways and alveoli of the lung. This causes a quick rise in blood nicotine concentrations, but due to the eventual burnout of the cigarette, these levels also peak early and thereafter drop to lower levels.
Option D: Direct effects on nicotinic acetylcholine receptors (nAChRs), which are present and functional very early in the fetal brain [5] are also likely to contribute.