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Pregnancy Due Date Calculation:
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The pregnancy due date is calculated as 280 days (40 weeks) from the first day of the last menstrual period (LMP). This is known as Naegele's rule and is the standard method for estimating due dates.
The calculator uses the standard formula:
Explanation: This calculation assumes a regular 28-day menstrual cycle with ovulation occurring on day 14. The actual delivery date may vary by ±2 weeks.
Details: Knowing the estimated due date helps healthcare providers monitor fetal development, schedule important prenatal tests, and determine if the pregnancy is progressing normally.
Tips: Enter the first day of your last menstrual period (LMP) in the format YYYY-MM-DD. The calculator will add 280 days (40 weeks) to this date.
Q1: How accurate is this due date calculation?
A: Only about 5% of women deliver on their exact due date. Most deliver within 2 weeks before or after.
Q2: What if my cycle isn't 28 days?
A: For women with longer or irregular cycles, an ultrasound dating scan may be more accurate.
Q3: Can the due date change?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements.
Q4: What's considered full term?
A: Between 37 weeks and 41 weeks 6 days. After 42 weeks is considered post-term.
Q5: How is this different from conception date?
A: Conception typically occurs about 2 weeks after LMP, so the fetal age is about 2 weeks less than the gestational age.