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Pregnancy Calculation Formula:
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The Pregnancy Calculator Based On LMP estimates the due date and current gestational age using the last menstrual period (LMP). This is the most common method for dating pregnancies in clinical practice.
The calculator uses the standard pregnancy calculation formula:
Where:
Explanation: This calculation assumes a regular 28-day menstrual cycle with ovulation occurring on day 14. The due date is calculated by adding 280 days (40 weeks) to the first day of the last menstrual period.
Details: Accurate pregnancy dating is crucial for monitoring fetal development, scheduling prenatal tests, determining gestational age for delivery decisions, and identifying potential complications like preterm or post-term pregnancy.
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 LMP-Based Dating?
A: LMP dating is generally accurate for women with regular cycles. For irregular cycles or uncertain dates, ultrasound dating in the first trimester is more reliable.
Q2: What If My Cycle Isn't 28 Days?
A: For cycles longer or shorter than 28 days, adjustments may be needed. Add or subtract the difference from 28 days to get a more accurate due date.
Q3: When Should I Confirm With Ultrasound?
A: Early ultrasound (6-12 weeks) can provide the most accurate dating. Later ultrasounds are less reliable for establishing due dates.
Q4: Can The Due Date Change?
A: Yes, healthcare providers may adjust the due date based on ultrasound findings, especially if there's a significant discrepancy from LMP dating.
Q5: What Percentage Deliver On Their Due Date?
A: Only about 5% of women deliver exactly on their due date. Most deliver within two weeks before or after the estimated date.