Why Calculate Gestational Age?
Calculating gestational age helps monitor fetal development, schedule prenatal tests, and determine accurate due dates. Understanding pregnancy weeks ensures proper medical care and helps track important milestones in fetal growth. Accurate dating improves pregnancy outcomes and helps identify potential complications early.
Gestational Age Calculator
Calculation Formula
Gestational Age = (Current Date - Last Menstrual Period Date) ÷ 7 days
If using due date: Gestational Age = 40 weeks - ((Due Date - Current Date) ÷ 7 days)
Step-by-Step Calculation Process
| Step | Action | Description |
|---|---|---|
| 1 | Identify LMP | Note first day of last menstrual period |
| 2 | Count Days | Calculate days between LMP and current date |
| 3 | Convert to Weeks | Divide total days by 7 |
| 4 | Adjust if Needed | Consider ultrasound dating for accuracy |
Pros and Cons
Advantages:
- Simple calculation method requiring only calendar dates
- Helps establish standardized pregnancy timeline
- Essential for scheduling prenatal tests and screenings
- Provides basis for fetal growth assessments
Disadvantages:
- Assumes regular 28-day menstrual cycles
- Less accurate for irregular periods
- Doesn't account for conception date variations
- Requires ultrasound confirmation for precision
FAQs
1. How accurate is LMP-based gestational age?
LMP dating assumes regular 28-day cycles and ovulation on day 14. While useful for initial estimation, ultrasound dating between 8-12 weeks provides more accurate results, especially for women with irregular cycles.
2. Can I calculate gestational age without LMP?
Yes, through ultrasound measurements of fetal size. Early pregnancy ultrasounds (6-9 weeks) can estimate gestational age within 3-5 days accuracy using crown-rump length measurements.