1. How Is Pregnancy Calculated By Ultrasound?

Ultrasound dating is the most accurate method for determining gestational age in pregnancy. It uses various fetal measurements to estimate how far along the pregnancy is, providing crucial information for prenatal care and delivery planning.

2. How Does the Calculator Work?

The calculator uses established ultrasound measurement formulas:

Common Measurement Parameters:

• Crown-Rump Length (CRL) - Most accurate in first trimester
• Biparietal Diameter (BPD) - Head measurement
• Femur Length (FL) - Thigh bone measurement
• Abdominal Circumference (AC) - Abdominal measurement

Explanation: Each measurement parameter has specific regression equations that correlate fetal size with gestational age.

3. Importance of Ultrasound Dating

Details: Accurate gestational dating is essential for proper prenatal care, identifying growth abnormalities, determining viability, and planning delivery timing.

4. Using the Calculator

Tips: Enter the ultrasound measurement in centimeters, select the appropriate measurement parameter, and click calculate. Ensure measurements are taken by qualified professionals.

5. Frequently Asked Questions (FAQ)

Q1: Which measurement is most accurate for dating?
A: Crown-rump length in the first trimester (7-13 weeks) is most accurate (±3-5 days). Later measurements have wider margins of error.

Q2: How accurate is ultrasound dating?
A: Accuracy varies by trimester: 1st trimester ±3-5 days, 2nd trimester ±7-10 days, 3rd trimester ±2-3 weeks.

Q3: When should ultrasound dating be performed?
A: Ideally between 8-13 weeks for most accurate dating. Can be done later if LMP is uncertain.

Q4: What if ultrasound date differs from LMP date?
A: Ultrasound dating typically takes precedence, especially if the difference is more than 5-7 days in first trimester.

Q5: Can ultrasound detect exact conception date?
A: No, ultrasound estimates gestational age from the first day of last menstrual period, not conception date.