## Core Concept
The expected date of delivery (EDD) is an estimate of when a pregnant woman is likely to give birth. It is calculated based on the first day of her last menstrual period (LMP) and assumes a regular 28-day menstrual cycle with ovulation on day 14. However, only a small percentage of women deliver on their exact EDD.

## Why the Correct Answer is Right
Studies have shown that approximately 4-5% of women deliver on their exact expected date of delivery. This low percentage is due to various factors, including variations in menstrual cycle length, ovulation timing, and gestational age at delivery. The EDD is merely an estimate, and actual delivery dates can vary.

## Why Each Wrong Option is Incorrect
* **Option A:** This option suggests a much higher percentage than actual, which does not align with clinical data.
* **Option B:** Similarly, this option overestimates the percentage of women delivering on their EDD.
* **Option D:** This option underestimates the percentage, as the actual figure is higher.

## Clinical Pearl / High-Yield Fact
A useful clinical pearl to remember is that only about 4-5% of women deliver on their exact EDD. Additionally, it's essential to consider that a normal gestation period ranges from 37 weeks to 42 weeks, and deliveries within this range are considered term.

## Correct Answer: C. 5%