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Pregnancy Wheel Calculation:
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The LMP Pregnancy Calculator Wheel, also known as a gestation calculator or pregnancy wheel, estimates the due date and tracks pregnancy progress based on the last menstrual period (LMP). It uses Naegele's rule to calculate the estimated delivery date.
The calculator uses the standard pregnancy calculation formula:
Where:
Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The 280 days represents 40 weeks of gestation from the LMP.
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 appropriate fetal growth and identify potential complications.
Tips: Enter the first day of your last menstrual period. The calculator will provide your estimated due date and current gestational age. Remember that only about 5% of babies are born exactly on their due date.
Q1: How accurate is the LMP method?
A: The LMP method is reasonably accurate for women with regular cycles. Ultrasound dating in the first trimester is more precise and may adjust the due date.
Q2: What if I have irregular periods?
A: For irregular cycles, early ultrasound dating is recommended as the LMP method may be less accurate.
Q3: Why 280 days instead of 9 months?
A: Pregnancy is calculated as 40 weeks from LMP, which equals 280 days. This differs from calendar months due to varying month lengths.
Q4: When should I confirm with ultrasound?
A: An ultrasound between 8-12 weeks provides the most accurate dating and should be used to confirm or adjust the LMP-based due date.
Q5: Can the due date change?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements, especially if there's a significant difference from LMP dating.