Home
Back
LMP Calculation Formula:
| From: | To: |
LMP (Last Menstrual Period) calculation is a method used in obstetrics to estimate the start date of pregnancy by working backwards from the current gestational age. This calculation helps determine the estimated due date and monitor fetal development.
The calculator uses the LMP calculation formula:
Where:
Explanation: The formula calculates backwards from the current date by subtracting the number of days equivalent to the gestational age (1 week = 7 days).
Details: Accurate LMP calculation is crucial for determining gestational age, estimating due dates, scheduling prenatal tests, and monitoring fetal growth and development throughout pregnancy.
Tips: Enter the current date (or any reference date) and the known gestational age in weeks. The calculator will compute the corresponding LMP date. Gestational age should be between 4-45 weeks for meaningful results.
Q1: Why is LMP important in pregnancy dating?
A: LMP provides the baseline for calculating gestational age and estimated due date, which are essential for prenatal care and monitoring fetal development.
Q2: How accurate is LMP-based dating?
A: LMP dating is generally accurate for women with regular menstrual cycles. For irregular cycles or uncertain dates, ultrasound dating may be more reliable.
Q3: What if I don't know my exact gestational age?
A: If gestational age is uncertain, an ultrasound examination can provide more accurate dating, especially in the first trimester.
Q4: Can this calculator be used for IVF pregnancies?
A: For IVF pregnancies, the calculation should be based on the embryo transfer date rather than LMP for greater accuracy.
Q5: What is the normal range for gestational age?
A: A full-term pregnancy typically ranges from 37-42 weeks gestational age, with 40 weeks being the standard duration.