1. What is the ACOG Gestational Age Calculation?

The ACOG (American College of Obstetricians and Gynecologists) method calculates gestational age by counting the number of days since the first day of the last menstrual period (LMP) and dividing by 7 to convert to weeks. This is the standard method used in obstetrics.

2. How Does the Calculator Work?

The calculator uses the ACOG standard formula:

Where:

• Current Date — Today's date or any date you want to calculate for
• LMP — First day of the last menstrual period
• 7 — Number of days in a week

Explanation: The calculation assumes conception occurred approximately 2 weeks after the LMP, which is standard in obstetric dating.

3. Importance of Gestational Age

Details: Accurate gestational age calculation is crucial for prenatal care, determining fetal growth standards, scheduling important tests, and managing high-risk pregnancies.

4. Using the Calculator

Tips: Enter the first day of the last menstrual period and the current date (defaults to today). The calculator will determine how many weeks pregnant this corresponds to.

5. Frequently Asked Questions (FAQ)

Q1: What if I don't know my LMP?
A: If LMP is unknown or cycles were irregular, an ultrasound measurement in early pregnancy (especially first trimester) provides the most accurate dating.

Q2: How accurate is this method?
A: For women with regular 28-day cycles, it's very accurate. For irregular cycles, ultrasound dating may be needed.

Q3: Why does pregnancy dating include the 2 weeks before conception?
A: This is standard obstetric practice as the menstrual cycle is more easily observed than the exact moment of conception.

Q4: What is Naegele's rule for due date?
A: Naegele's rule estimates the due date as LMP + 1 year - 3 months + 7 days (equivalent to 40 weeks from LMP).

Q5: When should I see a doctor for pregnancy confirmation?
A: Contact your healthcare provider as soon as you have a positive pregnancy test for initial prenatal care.