## Core Concept
Lochia refers to the vaginal discharge that occurs after childbirth, representing the process of uterine healing and clearance of debris. It transitions through different colors, indicating the progression of healing. **Lochia rubra**, the initial stage, is characterized by its red or brownish color due to the presence of blood.

## Why the Correct Answer is Right
Lochia rubra is seen in the first 2-3 days postpartum. This stage is dominated by blood and remnants of the decidua, hence its coloration. The **progression of lochia** is as follows: rubra (red), serosa (pinkish or brownish), and alba (whitish or creamy), reflecting the decrease in blood content and the increase in leukocytes and tissue debris.

## Why Each Wrong Option is Incorrect
- **Option A:** Less than 1 day. This is too short a duration for lochia rubra, as it typically lasts a few days.
- **Option B:** 4-5 days. While lochia does transition beyond this point, lochia rubra specifically refers to the initial bloody phase, usually not extending this long.
- **Option D:** More than 10 days. This duration is more characteristic of the total lochia duration rather than lochia rubra specifically.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the **duration and character of lochia** can be influenced by factors such as delivery method (vaginal vs. cesarean), presence of infection, or retained products of conception. Normally, lochia rubra lasts about 2-3 days, transitioning into lochia serosa.

## Correct Answer: B. 3 days.