**Core Concept**
Post-term pregnancy refers to a pregnancy that extends beyond 42 weeks of gestation. This condition is associated with various adverse outcomes due to changes in fetal and maternal physiology.

**Why the Correct Answer is Right**
Post-term pregnancies are associated with an increased risk of fetal distress, placental insufficiency, and meconium aspiration syndrome. The prolonged gestation period may lead to fetal hypoxia and acidosis, increasing the risk of stillbirth. Additionally, post-term pregnancies are associated with a higher risk of maternal gestational diabetes and hypertension.

**Why Each Wrong Option is Incorrect**
**Option A:** Post-term pregnancies are indeed associated with an increased risk of postpartum hemorrhage (PPH). This is due to the prolonged placental implantation and increased vascularity of the placental bed, which may lead to excessive uterine bleeding after delivery.

**Option B:** Placental abruption is a known complication of post-term pregnancies. This is due to the increased vascularity and fragility of the placental bed, which may lead to placental separation and bleeding.

**Option C:** Stillbirth is a significant risk associated with post-term pregnancies. This is due to fetal hypoxia and acidosis, which may lead to fetal demise.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that post-term pregnancies are often associated with an increased risk of fetal distress and stillbirth. It is essential for healthcare providers to closely monitor fetal well-being and initiate timely delivery to prevent adverse outcomes.

**Correct Answer:** D