malpresentation
Medical term for abnormal fetal positioning during labor, such as breech or transverse lie.
When malpresentation is detected, a cesarean section is considered.
逆子 is a common, non-technical term for breech presentation, while 胎位異常 is a broader medical term covering all abnormal fetal positions.
Compound of 胎位 (fetal position) and 異常 (abnormality).