Smoking during pregnancy mainly doubles the chances that?

Smoking during pregnancy significantly impacts fetal development and increases the risk of various adverse outcomes. The selected answer highlights that smoking primarily doubles the chances of a baby being born prematurely or with low birth weight.

When a pregnant individual smokes, the chemicals in cigarettes can restrict the blood flow to the placenta, leading to reduced oxygen and nutrient delivery to the developing fetus. This can cause the fetus to grow more slowly, resulting in low birth weight, which is defined as weighing less than 5.5 pounds at birth. Moreover, smoking is a well-known risk factor for preterm labor, increasing the likelihood of premature delivery.

This association is supported by extensive research indicating that maternal smoking is linked to these specific outcomes, making this option the most accurate representation of the risks involved. Other outcomes, such as the baby being born with tremors or weighing over 9.5 pounds, are less commonly associated with smoking during pregnancy and don't reflect the primary concerns related to maternal smoking.