Gestational Age Calculator

This calculator helps you determine your pregnancy timeline, including gestational age, due date, and important milestones. Whether you’re using your last menstrual period, conception date, or ultrasound measurements, get accurate pregnancy dating and a comprehensive schedule of development stages and appointments.

Why Use This Calculator?

• Calculate current gestational age
• Determine estimated due date
• Track pregnancy milestones
• Plan prenatal appointments
• Monitor baby’s development
• Understand trimester timing

How to Use the Calculator

1. Choose Calculation Method:

   • Last Menstrual Period (LMP)
   • Conception Date
   • Ultrasound Measurements

2. Enter Required Information:

   • Date of LMP, or
   • Known conception date, or
   • Ultrasound date and measurements

3. Interpret Results:

   • Current gestational age
   • Trimester information
   • Due date estimate
   • Development milestones
   • Appointment schedule

Understanding Your Results

Gestational Age

• Measured from first day of LMP
• Typically 40 weeks total
• Divided into three trimesters
• Includes two-week pre-conception period

Trimesters

1. First Trimester (Weeks 1-13)

   • Early development
   • Organ formation
   • Highest risk period

2. Second Trimester (Weeks 14-26)

   • Rapid growth
   • Movement begins
   • Gender determination

3. Third Trimester (Weeks 27-40)

   • Final development
   • Weight gain
   • Preparation for birth

Development Milestones

Early Pregnancy (Weeks 1-12)

• Week 4: Implantation
• Week 6: Heartbeat detectable
• Week 8: Major organs forming
• Week 12: End of first trimester

Mid Pregnancy (Weeks 13-27)

• Week 16: Movement may be felt
• Week 20: Detailed ultrasound
• Week 24: Viability milestone
• Week 28: Third trimester begins

Late Pregnancy (Weeks 28-40)

• Week 32: Lung development
• Week 36: Baby drops
• Week 37: Early term begins
• Week 40: Due date

Prenatal Appointments

First Trimester

• Week 8: Initial prenatal visit
• Week 12: NT scan
• Basic blood work
• Medical history review

Second Trimester

• Week 16: Screening tests
• Week 20: Anatomy scan
• Week 24: Glucose test
• Regular check-ups

Third Trimester

• Week 28: Tdap vaccine
• Week 36: Group B strep test
• Week 38: Weekly visits
• Birth preparation

Calculation Methods

1. Last Menstrual Period (LMP)

• Most common method
• Counts from first day of last period
• Standard medical dating
• May be less accurate if cycles irregular

2. Conception Date

• More precise if known
• Usually 2 weeks after LMP
• Used for assisted reproduction
• Adjusted to match LMP dating

3. Ultrasound Dating

• Most accurate method
• Especially reliable before 20 weeks
• Based on fetal measurements
• May adjust LMP-based dates

Tips for Accuracy

1. Record Keeping

   • Track menstrual cycles
   • Note conception date if known
   • Save ultrasound reports
   • Document important dates

2. Regular Updates

   • Attend all appointments
   • Get recommended scans
   • Update calculations
   • Track changes

3. Consistency Check

   • Compare different methods
   • Note significant discrepancies
   • Discuss with healthcare provider
   • Maintain records

Common Questions

How accurate is the due date?

• Only 5% deliver on exact date
• Most deliver ±2 weeks
• More accurate with early ultrasound
• Regular updates may adjust date

What if my cycles are irregular?

• Use ultrasound dating
• Consider conception date
• Discuss with provider
• May need adjustments

When should I schedule appointments?

• Follow recommended schedule
• Adjust for risk factors
• Book early for availability
• Maintain regular visits

Medical Considerations

High-Risk Factors

• Advanced maternal age
• Medical conditions
• Multiple pregnancies
• Previous complications

When to Seek Care

• Bleeding or spotting
• Severe pain
• Decreased movement
• Concerning symptoms

Additional Monitoring

• More frequent visits
• Extra ultrasounds
• Specialized tests
• Close observation

Technical Notes

Calculation Method

• Standard pregnancy = 280 days
• Gestational age in weeks and days
• Adjustments for dating methods
• Regular updates as needed

Accuracy Factors

• Cycle regularity
• Dating method used
• Timing of measurements
• Multiple confirmations

Limitations

• Natural variation
• Individual differences
• Method accuracy
• Need for updates

Additional Resources

1. Pregnancy Education

   • Childbirth classes
   • Nutrition guidance
   • Exercise recommendations
   • Birth preparation

2. Healthcare Support

   • Provider selection
   • Hospital information
   • Insurance coverage
   • Emergency contacts

3. Planning Tools

   • Birth plan template
   • Hospital checklist
   • Appointment tracker
   • Development diary