**Core Concept**
Multipara women are those who have given birth two or more times, whereas primipara women are those who have given birth only once. The question is testing the difference in obstetric complications between multipara and primipara women.

**Why the Correct Answer is Right**
In multipara women, the risk of postpartum hemorrhage (PPH) is lower due to uterine atony being less common, as the uterus is more efficient in contracting after multiple pregnancies. This is because the uterus develops a more efficient contractile pattern with each subsequent pregnancy, making it less prone to atony.

**Why Each Wrong Option is Incorrect**
**Option A:** Postpartum hemorrhage (PPH) is actually more common in multipara women due to atony being less likely, but other causes like retained placental tissue or lacerations are more common in multipara women who may have had more complicated deliveries. However, it's not the most correct option to choose as the question's exception.
**Option B:** Uterine atony is actually less common in multipara women, as they have a more efficient uterine contractile pattern. However, this is the correct answer to the question, so we won't be explaining it further.
**Option C:** Placenta previa is actually more common in multipara women due to the increased risk of placental implantation over a previous scar from a cesarean section or other uterine surgery. This makes it a less likely correct answer.
**Option D:** Placental abruption is actually more common in primipara women due to the increased risk of uteroplacental insufficiency in first-time mothers. This makes it a less likely correct answer.

**Clinical Pearl / High-Yield Fact**
In multipara women, the risk of postpartum hemorrhage due to uterine atony is lower, but other complications like retained placental tissue or lacerations may be more common due to the increased risk of complications in subsequent pregnancies.

**Correct Answer:** B. Uterine atony is actually less common in multipara women, as they have a more efficient uterine contractile pattern.