**Core Concept**
Cleft lip and palate repair involves a multidisciplinary approach to optimize outcomes. The timing of surgical intervention is critical to minimize long-term sequelae. **The optimal age for primary cleft lip repair is a subject of debate among plastic surgeons**.

**Why the Correct Answer is Right**
The current consensus is to perform cleft lip repair between 3 to 6 months of age. This timing allows for optimal tissue pliability and minimizes the risk of scarring and tissue loss. Additionally, early repair facilitates feeding and reduces the risk of aspiration. The **lip tension and tissue elasticity** are optimal during this period, making it an ideal time for surgical intervention.

**Why Each Wrong Option is Incorrect**
**Option A:** Performing cleft lip repair at birth is not recommended due to the high risk of **airway compromise** and **aspiration**. The infant's airway is delicate, and any surgical intervention may exacerbate these risks.
**Option B:** Delaying cleft lip repair until 1 year of age may lead to **poor lip tension** and **scarring**, making the repair more challenging and increasing the risk of long-term complications.
**Option C:** Repairing cleft lip at 6 months of age is not early enough, as the **lip tissue is still relatively rigid** and may not provide optimal results.
**Option D:** There is no consensus on repairing cleft lip at 18 months of age, as the **lip tissue has already become more rigid**, and the risk of scarring and long-term complications increases.

**Clinical Pearl / High-Yield Fact**
The timing of cleft lip repair is critical, and a **delay of more than 6 months can lead to suboptimal results**.

**Correct Answer: B. 1 year of age**