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Gestational Weeks Calculation:
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Gestational age calculation determines how far along a pregnancy is by measuring the time elapsed since the first day of the last menstrual period (LMP). This is the standard method used by healthcare providers to track pregnancy progression.
The calculator uses the standard obstetric formula:
Where:
Explanation: Pregnancy dating begins from the first day of the last menstrual period, which is typically about two weeks before conception actually occurs.
Details: Accurate gestational dating is crucial for appropriate prenatal care, scheduling screenings and tests, monitoring fetal development, and determining the estimated due date.
Tips: Enter the first day of your last menstrual period and the current date (or any date you want to check). The calculator will determine how many weeks and days pregnant you are as of that date.
Q1: Why is pregnancy calculated from LMP rather than conception?
A: LMP is used because it's typically easier to recall than the exact conception date, and it provides a standardized method for healthcare providers worldwide.
Q2: How accurate is LMP dating?
A: LMP dating is generally accurate within about ±5 days when the menstrual cycles are regular. Ultrasound dating in early pregnancy can provide more precise estimates.
Q3: What if I don't remember my LMP exactly?
A: If LMP is uncertain, an early pregnancy ultrasound (before 14 weeks) provides the most accurate gestational age assessment.
Q4: Does this work for IVF pregnancies?
A: For IVF pregnancies, gestational age is typically calculated from the egg retrieval date or embryo transfer date, plus 14 days.
Q5: How is due date calculated from gestational age?
A: The estimated due date is calculated as LMP + 280 days (40 weeks), often using Naegele's rule: LMP + 1 year - 3 months + 7 days.