Which condition is a contraindication for performing an external cephalic version (ECV)?

The correct answer pertains to the contraindication for performing an external cephalic version (ECV), focusing on multiple gestation pregnancies. In cases of multiple gestations, attempting an ECV can present significant risks. Each fetus has its own position and space in the uterus, making it difficult to manipulate one fetus without affecting the others. Additionally, multiple gestation carries a higher risk of complications such as fetal distress, preterm labor, or umbilical cord issues during the procedure.

In contrast, a non-engaged fetal breech does not inherently contraindicate ECV since the procedure is often aimed at changing the position of breech fetuses. A reactive nonstress test indicates that the fetus is experiencing adequate oxygenation and is not in distress, which can actually support the decision to proceed with ECV. Abnormal amniotic fluid levels might raise concerns, but the condition itself does not universally rule out ECV; fluid levels need to be evaluated in the broader context of maternal and fetal well-being. Therefore, multiple gestation is the most definitive contraindication among the listed conditions for performing an ECV.