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Pregnancy Date Calculation:
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Pregnancy date calculation is a standard method to estimate the due date of a pregnancy based on the first day of the last menstrual period (LMP). The estimated due date (EDD) is calculated by adding 280 days (40 weeks) to the LMP.
The calculator uses the standard pregnancy dating formula:
Where:
Explanation: This calculation is based on the average human gestation period of 280 days (40 weeks) from the first day of the last menstrual period. It assumes a regular 28-day menstrual cycle with ovulation occurring on day 14.
Details: Accurate pregnancy dating is crucial for monitoring fetal development, scheduling prenatal tests, determining gestational age, and planning for delivery. It helps healthcare providers track the baby's growth and identify any potential complications.
Tips: Enter the first day of your last menstrual period in the date field. The calculator will provide your estimated due date and current gestational age. Ensure you enter the correct date for accurate results.
Q1: How accurate is the 280-day calculation?
A: While 280 days is the average, only about 5% of women deliver exactly on their due date. Most deliveries occur within two weeks before or after the estimated date.
Q2: What if I have irregular periods?
A: For women with irregular cycles, an early ultrasound (first trimester) provides more accurate dating than LMP-based calculation.
Q3: Why is pregnancy calculated from LMP and not conception?
A: LMP is used because it's a definite date that most women can recall, while the exact conception date is often unknown.
Q4: Can the due date change during pregnancy?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements, especially if there's a significant difference from LMP-based calculation.
Q5: What is Naegele's rule?
A: This is the traditional method: add 7 days to LMP, then subtract 3 months. Our calculator uses the more precise 280-day calculation.