Which of the following is NOT an etiology of fetal growth restriction?

Fetal growth restriction (FGR) arises from a variety of conditions that can impair the normal growth and development of the fetus. When analyzing the question concerning the etiology of FGR, it is crucial to understand how each factor contributes to the condition.

Pregestational diabetes mellitus is associated with complications that can lead to fetal growth issues, primarily due to maternal hyperglycemia affecting placental function and fetal metabolism. Substance abuse, including tobacco and alcohol, can negatively impact placental perfusion and fetal development, making it a relevant factor. Genetic disorders can also lead to FGR due to chromosomal aberrations or hereditary conditions affecting growth.

In contrast, first trimester bleeding, while concerning and often requiring evaluation for potential miscarriage or other complications, does not have a direct association with fetal growth restriction. While it can signal underlying problems in the pregnancy, it is not categorized as a direct cause of FGR. Thus, this choice correctly identifies a factor that does not contribute to the etiology of fetal growth restriction.