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Pregnancy Calculation Formula:
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Pregnancy duration calculation determines how many weeks and days pregnant you are based on your Last Menstrual Period (LMP) date. This is the standard method used by healthcare providers to estimate gestational age.
The calculator uses the following formula:
Where:
Explanation: The calculation counts the number of days between your LMP and the current date, then converts this to weeks and days.
Details: Accurate pregnancy dating is crucial for monitoring fetal development, scheduling prenatal tests at appropriate times, and determining your estimated due date (typically 40 weeks from LMP).
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 exactly how many weeks and days pregnant you are on that date.
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. Pregnancy is calculated as 40 weeks from LMP, which includes approximately 2 weeks before conception actually occurred.
Q2: What if I don't know my LMP exactly?
A: If you're unsure of your LMP, an ultrasound in early pregnancy can provide a more accurate gestational age estimate. This calculator assumes you know your LMP date.
Q3: How accurate is this calculation?
A: This provides a good estimate for women with regular 28-day cycles. If your cycles are irregular, the calculation may be less accurate.
Q4: Does this work for IVF pregnancies?
A: For IVF pregnancies, calculation is typically based on embryo transfer date rather than LMP. Consult with your fertility specialist for accurate dating.
Q5: When should I see a doctor to confirm pregnancy?
A: Most healthcare providers recommend scheduling your first prenatal appointment around 8 weeks of pregnancy, but this may vary based on your medical history and provider preferences.