The substances that are part of tobacco have very harmful effects on the developing fetus. Nicotine causes increased constriction of the blood vessels, resulting in reduced blood supply to the placenta. In addition, carbon monoxide binds to red blood cells and displaces oxygen. As a result, placental insufficiency occurs: less oxygen and nutrients reach the fetus for growth.
On the other hand, newborn babies born to mothers who smoke during pregnancy show irritability and tremors due to withdrawal syndrome. Childbirth interrupts the continuous exposure to nicotine and, therefore, these symptoms will appear in the baby in the first 24 to 48 hours of life.