Which of the following is a postnatal effect of smoking during pregnancy?

Smoking during pregnancy has significant adverse effects on the developing fetus, and one of the postnatal consequences is an increased risk of respiratory infections in infants. Maternal smoking can lead to impaired lung development and function in the newborn, which makes them more susceptible to respiratory illnesses. This is primarily due to the exposure to harmful chemicals in tobacco smoke that can affect the integrity of lung tissue and the immune system of the developing baby.

In contrast to the other options, which imply positive or neutral outcomes, the reality is that smoking is linked to numerous health problems rather than benefits. For instance, there is no evidence to support the idea that smoking could improve reading scores or lead to higher average height or reduce hyperactivity. These factors are typically influenced by a range of developmental, environmental, and genetic factors, but smoking during pregnancy is known to have detrimental impacts overall on child health, including respiratory issues. Therefore, the link between smoking in pregnancy and increased rates of respiratory infections postnatally is well-documented and a critical concern in addiction medicine and public health.