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Pregnancy Week Calculation Formula:
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Gestational age calculation determines how far along a pregnancy is based on the first day of the last menstrual period (LMP). This is the standard method used by healthcare providers to track pregnancy progression.
The calculator uses the standard gestational age formula:
Where:
Explanation: The calculation counts the number of full weeks between the LMP and the current date, providing the gestational age in weeks and days.
Details: Accurate pregnancy dating is crucial for monitoring fetal development, scheduling appropriate prenatal tests, determining expected due date, and making important clinical decisions throughout pregnancy.
Tips: Enter the first day of your last menstrual period and the current date (or any date you want to check). The calculator will determine how many weeks and days pregnant you are at that point in time.
Q1: Why is pregnancy calculated from LMP rather than conception?
A: LMP is used because it's typically easier to recall than the exact conception date, and it provides a standardized method for healthcare providers worldwide.
Q2: How accurate is LMP dating?
A: LMP dating is generally accurate within ±2 weeks. Early ultrasound dating (before 14 weeks) is considered more precise for establishing gestational age.
Q3: What if I don't know my LMP exactly?
A: If unsure about LMP, an early ultrasound provides the most accurate dating. Healthcare providers may use both methods to establish the most reliable due date.
Q4: Does this work for irregular cycles?
A: LMP dating assumes a regular 28-day cycle. Women with irregular cycles may need ultrasound dating for more accurate results.
Q5: When should I see a healthcare provider?
A: Contact a healthcare provider as soon as you suspect pregnancy for confirmation, accurate dating, and to begin prenatal care.