Meconium should be excreted by a newborn by … days?

**Core Concept**
The passage of meconium is a critical indicator of gastrointestinal tract patency and function in newborns. **Meconium** is the first feces of a newborn, composed of materials ingested during the time spent in the uterus.

**Why the Correct Answer is Right**
Typically, a newborn should pass meconium within the first 48 hours of life. This timeline is crucial because failure to pass meconium within this period may indicate an issue such as intestinal obstruction. The **gastrointestinal tract** starts practicing contractions and movements in utero, and after birth, it's essential for the newborn to clear out the meconium to start the normal process of digestion and absorption.

**Why Each Wrong Option is Incorrect**
**Option A:** Passing meconium by 24 hours might not capture all normal variations, as some babies might take a bit longer.
**Option C:** While most babies pass meconium within the first couple of days, waiting until 72 hours or more might not be necessary for all normal newborns.
**Option D:** This option is too broad and does not accurately reflect the typical timeline for meconium passage.

**Clinical Pearl / High-Yield Fact**
It's essential to monitor the passage of meconium in newborns, especially those with a history of **intestinal obstruction** or other gastrointestinal anomalies. Delayed passage of meconium can be an early sign of conditions such as **Hirschsprung's disease**.

**Correct Answer:** B. 48 hours.