**Question:** Incidence of preterm delivery in twin pregnancy is

A. higher
B. lower
C. equal to singleton pregnancy
D. lower in twins compared to singleton pregnancy

**Core Concept:** Preterm delivery refers to the birth of a baby before the full term (37 completed weeks) of gestation. In twin pregnancies, the risk of preterm delivery is generally higher compared to singleton pregnancies.

**Why the Correct Answer is Right:** Twin pregnancies have a higher risk of preterm delivery due to various factors, including:

1. **Competition for resources:** Twin placentas compete for essential nutrients, oxygen, and blood supply, leading to increased stress and inflammation, which may result in preterm labor.
2. **Prenatal complications:** Twin pregnancies are more prone to complications like preeclampsia, gestational diabetes, and intrauterine growth restriction, all of which can contribute to preterm delivery.
3. **Changes in cervical length and dilatation:** Twin pregnancies have a shorter cervix compared to singleton pregnancies, making them more susceptible to cervical length shortening and preterm labor.

**Why Each Wrong Option is Incorrect:**

1. **Option A (higher):** While twin pregnancies have a higher risk of preterm delivery, the correct answer states that the incidence is **not** higher compared to singleton pregnancies.
2. **Option B (lower):** This statement is incorrect, as twin pregnancies have a higher risk of preterm delivery.
3. **Option C (equal to singleton pregnancy):** Twin pregnancies actually have a **higher** risk of preterm delivery compared to singleton pregnancies, not equal.

**Clinical Pearl:**

Understanding the higher risk of preterm delivery in twin pregnancies helps healthcare providers monitor these patients more closely, implement preventative measures, and provide appropriate management strategies to reduce adverse outcomes for both babies and mothers.