In a ceain population, there were 4050 bihs in the last one year. There were 50 stillbihs. 50 infants died within 7 days whereas 150 died within 28 days. What is the Neonatal moality rate?

**Core Concept**
Neonatal mortality rate (NMR) is a measure of the number of deaths of infants within the first 28 days of life per 1000 live births. It is an important indicator of the quality of perinatal and neonatal care in a given population.

**Why the Correct Answer is Right**
To calculate the NMR, we need to use the following formula: (Number of deaths within 28 days / Number of live births) x 1000. In this population, there were 50 stillbirths, which are not included in the live births, and 150 deaths within 28 days. The number of live births is 4050 - 50 = 4000. Now, we can plug in the values: (150 / 4000) x 1000 = 37.5. Therefore, the NMR is 37.5 per 1000 live births.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not account for the stillbirths and the deaths within 7 days.
**Option B:** This option is incorrect because it uses the total number of births (4050) instead of the number of live births (4000).
**Option C:** This option is incorrect because it uses the number of deaths within 7 days (50) instead of the number of deaths within 28 days (150).

**Clinical Pearl / High-Yield Fact**
When calculating neonatal mortality rate, it is essential to exclude stillbirths and deaths within the first 7 days, as they are not included in the 28-day period.

**Correct Answer:** B.