1. What is Pregnancy Weeks Calculation?

Pregnancy weeks calculation based on Last Menstrual Period (LMP) is the standard method for estimating gestational age. It calculates how many weeks have passed since the first day of the woman's last menstrual period.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• \( \text{LMP} \) — First day of last menstrual period
• \( \text{Current Date} \) — Today's date or any specified date
• \( 7 \) — Days in a week

Explanation: The calculation counts the number of days between the LMP and current date, then converts to weeks by dividing by 7.

3. Importance of Pregnancy Dating

Details: Accurate pregnancy dating is crucial for proper prenatal care, timing of tests, monitoring fetal growth, and determining the due date (approximately 40 weeks from LMP).

4. Using the Calculator

Tips: Enter the first day of your last menstrual period and either today's date or any other date you want to check. The calculator will show how many weeks pregnant you would be on that date.

5. Frequently Asked Questions (FAQ)

Q1: Is this calculation accurate for everyone?
A: This assumes a regular 28-day cycle with ovulation around day 14. Women with irregular cycles may need ultrasound dating.

Q2: What if I don't remember my LMP?
A: An early ultrasound (first trimester) can provide the most accurate dating if LMP is unknown.

Q3: Why does pregnancy count include the 2 weeks before conception?
A: Pregnancy dating traditionally starts from LMP because this date is usually known, while conception date often isn't.

Q4: How does this relate to trimesters?
A: First trimester: weeks 1-12, second trimester: weeks 13-28, third trimester: weeks 29-40.

Q5: What if my cycle isn't 28 days?
A: For cycles longer than 28 days, add the difference to the calculation. For example, for a 35-day cycle, add 1 week to the result.