1. What is Pregnancy Weeks Calculation?

The pregnancy weeks calculation determines how many weeks have passed since the first day of the last menstrual period (LMP). This is the standard method for dating pregnancies in clinical practice.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• \( \text{LMP\_date} \) — First day of last menstrual period
• \( \text{Current\_date} \) — Date of calculation
• \( \text{floor} \) — Rounds down to nearest whole number

Explanation: The calculation counts complete weeks from LMP to current date, which is the standard obstetric dating method.

3. Importance of Pregnancy Dating

Details: Accurate pregnancy dating is crucial for proper prenatal care, timing of tests, monitoring fetal growth, and determining due dates.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period and the current date. The calculator will determine how many complete weeks of pregnancy have passed.

5. Frequently Asked Questions (FAQ)

Q1: What if I don't know my LMP?
A: If LMP is unknown, an ultrasound in early pregnancy can provide dating. The most accurate dating comes from first trimester ultrasounds.

Q2: Is this the same as gestational age?
A: Yes, pregnancy weeks calculated from LMP represent gestational age. Fetal age is about 2 weeks less than gestational age.

Q3: What if my cycles are irregular?
A: The calculation assumes a 28-day cycle. For irregular cycles, ultrasound dating is more accurate.

Q4: When is the due date calculated?
A: The estimated due date is 40 weeks (280 days) from the first day of the LMP.

Q5: Can this be used after IVF?
A: For IVF pregnancies, dating is based on embryo transfer date, not LMP.