**Core Concept**
A trained birth attendant (TBA) is a skilled health professional who provides care to women during childbirth. The World Health Organization (WHO) defines a trained birth attendant as a person who has received training in the skills necessary to manage uncomplicated deliveries and provide basic emergency obstetric care.

**Why the Correct Answer is Right**
The correct answer is a skilled midwife or a nurse who has received training in the skills necessary to manage uncomplicated deliveries and provide basic emergency obstetric care. This training typically includes skills such as:
* Recognizing and managing complications during labor and delivery
* Providing basic neonatal care
* Administering medications and performing minor surgical procedures
* Providing postpartum care to the mother and newborn

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a traditional birth attendant (TBA) is not necessarily a trained health professional and may not have the necessary skills to manage complications during childbirth.
**Option B:** This option is incorrect because a midwife or nurse who is not trained in basic emergency obstetric care is not considered a trained birth attendant.
**Option C:** This option is incorrect because a layperson or family member who has not received formal training in childbirth care is not considered a trained birth attendant.

**Clinical Pearl / High-Yield Fact**
It's worth noting that the term "trained birth attendant" is often used interchangeably with "skilled birth attendant," but the WHO specifically defines a skilled birth attendant as a midwife or a doctor who has received training in the skills necessary to manage uncomplicated deliveries and provide basic emergency obstetric care.

**Correct Answer:** D. Layperson or family member