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Pregnancy Week Calculation:
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Pregnancy week calculation estimates gestational age based on the first day of your last menstrual period (LMP). This is the standard method used by healthcare providers to track pregnancy progress and estimate due dates.
The calculator uses the following formula:
Where:
Explanation: The calculation counts the number of days from LMP to current date, then converts to weeks by dividing by 7 and taking the floor value.
Details: Accurate pregnancy dating is essential for monitoring fetal development, scheduling prenatal tests, determining viability, and estimating the due date. It helps healthcare providers track if the pregnancy is progressing normally.
Tips: Enter the first day of your last menstrual period and the current date (or any date you want to check). The calculator will display your pregnancy duration in weeks and days.
Q1: Why is pregnancy calculated from LMP instead of 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 about 2 weeks before actual conception.
Q2: What if I don't know my exact LMP?
A: If you're unsure of your LMP, an ultrasound in early pregnancy can provide a more accurate gestational age measurement.
Q3: How accurate is LMP dating?
A: LMP dating is generally accurate for women with regular cycles. For irregular cycles, ultrasound dating is more reliable.
Q4: What is considered full-term pregnancy?
A: Full-term pregnancy is between 39 weeks 0 days and 40 weeks 6 days. Early term is 37-38 weeks, late term is 41 weeks, and post-term is 42+ weeks.
Q5: When should I see a healthcare provider?
A: Schedule your first prenatal appointment as soon as you suspect pregnancy, typically around 8 weeks gestation for initial confirmation and dating.