1. What Is Pregnancy Weeks Calculation?

Pregnancy weeks calculation determines how far along a pregnancy has progressed based on the first day of the last menstrual period (LMP). This method is the standard clinical approach for estimating gestational age.

2. How Does The Calculator Work?

The calculator uses the standard pregnancy dating formula:

Where:

• \( \text{LMP} \) — First day of last menstrual period
• \( \text{Current Date} \) — Today's date or any specified date
• \( \left\lfloor \right\rfloor \) — Floor function (round down to nearest whole number)

Explanation: The calculation counts the number of complete weeks that have passed since the first day of your last menstrual period.

3. Importance Of Pregnancy Dating

Details: Accurate pregnancy dating is essential for monitoring fetal development, scheduling prenatal tests, determining due date, and making important healthcare decisions throughout pregnancy.

4. Using The Calculator

Tips: Enter the first day of your last menstrual period and the current date (defaults to today). Ensure dates are entered in the correct format and that LMP date is before current date.

5. Frequently Asked Questions (FAQ)

Q1: Why use LMP instead of conception date?
A: LMP is used because it's typically more reliably known than conception date and provides a standardized method for healthcare providers worldwide.

Q2: How accurate is this calculation?
A: This method is clinically standard but may be adjusted by ultrasound dating, especially if there's uncertainty about LMP or irregular cycles.

Q3: What if I don't remember my exact LMP?
A: Use your best estimate. Early pregnancy ultrasound (6-13 weeks) can provide more accurate dating if LMP is uncertain.

Q4: Does this work for IVF pregnancies?
A: For IVF pregnancies, dating is typically based on embryo transfer date rather than LMP for greater accuracy.

Q5: What are the pregnancy trimesters?
A: First trimester: weeks 1-13, Second trimester: weeks 14-27, Third trimester: weeks 28-40+.