Gest Age LMP Calculator

Gestational Age Formula:

\[ \text{Gestational Age (weeks)} = \left\lfloor \frac{\text{Current Date} - \text{LMP}}{7} \right\rfloor \]

Gestational Age:

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1. What is Gestational Age Using LMP?

Gestational age calculated from the Last Menstrual Period (LMP) is the standard method for estimating pregnancy duration. It measures the time elapsed since the first day of the woman's last menstrual period and is expressed in weeks and days.

2. How Does the Calculator Work?

The calculator uses the gestational age formula:

\[ \text{Gestational Age (weeks)} = \left\lfloor \frac{\text{Current Date} - \text{LMP}}{7} \right\rfloor \]

Where:

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

Explanation: The calculation counts the number of complete weeks between LMP and current date, providing the gestational age in weeks plus any remaining days.

3. Importance of Gestational Age Calculation

Details: Accurate gestational age determination is crucial for monitoring fetal development, scheduling prenatal tests, determining due date, and making clinical 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 (YYYY-MM-DD).

5. Frequently Asked Questions (FAQ)

Q1: Why use LMP instead of conception date?
A: LMP is more reliably known than conception date and provides a standardized method for calculating gestational age across healthcare providers.

Q2: How accurate is LMP dating?
A: LMP dating is generally accurate within ±2 weeks. Ultrasound dating in the first trimester is more precise and may be used to adjust dates if needed.

Q3: What if I have irregular periods?
A: For women with irregular cycles, LMP dating may be less accurate. Early ultrasound is recommended for more precise gestational age determination.

Q4: When should gestational age be confirmed?
A: Ideally confirmed by first-trimester ultrasound (before 14 weeks) for most accurate dating, especially if LMP is uncertain or cycles are irregular.

Q5: How is this different from fetal age?
A: Gestational age includes the approximately 2 weeks before conception, while fetal age (from conception) is about 2 weeks less than gestational age.