Due Date by LMP


Due Date by LMP

Ever wondered how doctors predict the due date for a baby’s birth? They don’t employ magic or mysterious insider stork knowledge. Instead, they use a method known as the Last Menstrual Period (LMP) calculation formula. It might not sound as mystical, but believe it or not, it’s pretty darn effective!

The formula is straightforward: Due Date = Last Menstrual Period + 280 days. It’s as simple as adding sugar to your coffee and just as effective!

Due Date Categories

Here are the various categories of due dates based on the LMP calculation.

LMP Calculation Range (Days) Interpretation
240-260 Early term
260-280 Full term
280-300 Late term
Over 300 Post-term

Examples of LMP Calculations

To better understand, let’s examine some examples of how the LMP calculation works for different individuals.

Individual LMP Date Due Date Calculation & Fun Fact
Jane Doe Feb 20 Nov 27 Feb 20 + 280 days = Nov 27. Looks like Jane will be putting the turkey in the oven earlier this year!

Calculation Methods

There are various methods of calculating due dates. Each has its own advantages, disadvantages, and accuracy levels.

Method Advantages Disadvantages Accuracy
LMP Calculation Simple Not always accurate 80%

Evolution of LMP Calculation

The concept of LMP calculation has evolved over time. Let’s take a look at the journey!

Period Method
Ancient Times Guesswork
18th Century LMP Calculation

Limitations of LMP Calculation

Despite its simplicity, the LMP Calculation does have some limitations:

  1. Accuracy: This method is not always accurate.
  2. Irregular periods: LMP Calculation is ineffective for those with irregular cycles.

Alternative Methods

There are alternative methods for calculating due dates, each with their own pros and cons.

Method Pros Cons
Ultrasound More accurate More expensive

FAQs on Due Date by LMP

1. What is LMP? Last Menstrual Period.

2. How accurate is the LMP calculation? The LMP calculation is about 80% accurate.

3. What if I have irregular periods? If you have irregular periods, the LMP calculation may not be as accurate.

4. Are there other methods to calculate the due date? Yes, ultrasound is another method used to calculate the due date.

5. How does ultrasound compare to LMP calculation? Ultrasound is more accurate but it is also more expensive.

6. How has the LMP calculation evolved over time? The LMP calculation method has evolved from guesswork in ancient times to a more precise formula in the 18th century.

7. What is considered a full term using the LMP calculation? A full term is considered to be between 260-280 days using the LMP calculation.

8. What does early term and late term mean? Early term is considered to be between 240-260 days and late term is considered to be between 280-300 days using the LMP calculation.

9. What if the LMP calculation is over 300 days? If the LMP calculation is over 300 days, it is considered post-term.

10. Where can I find more resources on LMP calculation? You can find more resources on the CDC website.


  1. CDC: Offers resources on pregnancy and due date calculation.