**Question:** Not a feature of postdated pregnancy:

A. Polyhydramnios
B. Polyhydramnios
C. Prolonged pregnancy (gestational age)
D. Premature rupture of membranes

**Core Concept:** Postdated pregnancy is a condition where the date of labor is deliberately advanced, typically in an attempt to improve the chances of a successful vaginal delivery or to prevent potential complications associated with a prolonged pregnancy.

**Why the Correct Answer is Right:** Polyhydramnios is a condition characterized by excessive amniotic fluid accumulation, which can lead to complications during childbirth. In postdated pregnancy, reducing the gestational age is the goal, so increasing amniotic fluid volume is not desirable.

**Why Each Wrong Option is Incorrect:**

A. Polyhydramnios (repeated): This is a feature of postdated pregnancy, not a feature that distinguishes postdated pregnancy from other conditions.
B. Polyhydramnios (correct): Postdated pregnancy does not involve intentionally increasing amniotic fluid volume; this would be counterproductive to the goal of reducing gestational age.
C. Prolonged pregnancy (gestational age): Although prolonged pregnancy is a risk factor for postdated pregnancy, it is not a feature that distinguishes postdated pregnancy from other conditions.
D. Premature rupture of membranes (correct): Postdated pregnancy aims to reduce gestational age, not to induce labor prematurely. Premature rupture of membranes would not be a feature of postdated pregnancy.

**Clinical Pearl:** It is essential for healthcare providers to understand the key features of postdated pregnancy and differentiate it from conditions like premature rupture of membranes, which is a feature of premature labor rather than postdated pregnancy. This distinction is crucial for appropriate management strategies and to prevent unnecessary complications.