What is a potential effect of smoking during pregnancy?

Smoking during pregnancy is associated with a number of adverse outcomes. One significant effect is an increased risk of ectopic pregnancy, where a fertilized egg implants outside of the uterus, most commonly in a fallopian tube. This condition can be life-threatening and typically requires medical treatment, often involving surgery. The toxic substances in cigarettes can negatively affect the reproductive system and increase the risk of complications during conception and early pregnancy.

In contrast, the other options suggest outcomes that are either typically not influenced positively by smoking or are generally false. For instance, smoking is linked to lower birth weights, increased risks of preterm delivery, and a higher likelihood of miscarriage, contrary to the notion of decreased risk of miscarriage or higher rates of full-term delivery. Thus, the association of smoking with ectopic pregnancy highlights the significant risks that smoking poses to a developing pregnancy.