Which of the following is NOT a risk factor for macrosomia?

Macrosomia, defined as a birth weight greater than 4,000 grams (approximately 8 pounds, 13 ounces), is influenced by several maternal factors. Uncontrolled gestational diabetes mellitus (GDM), a history of prior macrosomic infants, and excessive gestational weight gain are all established risk factors.

Uncontrolled GDM contributes to higher levels of glucose in the maternal bloodstream, leading to increased fetal insulin production and subsequent growth. A mother who has previously delivered a macrosomic infant is also at a higher risk of delivering another large baby, likely due to underlying hereditary and metabolic factors. Meanwhile, excessive gestational weight gain is associated with increased fetal size as the additional maternal weight can contribute to the fetus accumulating more fat and growth.

In contrast, maternal smoking is generally associated with lower birth weights due to its effects on placental function and fetal growth restriction. Therefore, it does not contribute to an increased risk of macrosomia and is not considered a risk factor in this context. This distinction is crucial in understanding the impact of various lifestyle factors on fetal development.