Tracking a pregnancy week-by-week helps expecting parents prepare for crucial fetal developmental milestones, scheduled medical screenings, and the physical changes accompanying each trimester. While nature follows its own schedule, clinical obstetrics relies on standardized mathematical formulas to determine a woman's Estimated Due Date (EDD) and current gestational age. Please note that while this calculator uses standard medical algorithms, ultrasound measurements performed by your healthcare provider offer the most definitive dating.
Gestational Age Baseline
In medical practice, pregnancy is calculated starting from the first day of your Last Menstrual Period (LMP), not the actual day of conception. A standard full-term pregnancy is charted as exactly 280 days (40 weeks).
How to Use This Calculator
- Select the calculation method (Last Menstrual Period, Conception Date, or Ultrasound Date).
- Input the corresponding date into the calendar field.
- Specify your average menstrual cycle length (the standard default is 28 days).
- Click Calculate to instantly view your precise gestational age, current trimester, and estimated delivery date.
Frequently Asked Questions (FAQ)
Why is pregnancy counted from the last period instead of conception?
The exact date of conception is often unknown because sperm can survive for several days inside the reproductive tract before fertilizing an egg. The first day of the last menstrual period is a tangible, observable date that doctors use globally to standardize the 40-week timeline.
How accurate is the estimated due date (EDD)?
The EDD is simply a statistical target. Only about 4% to 5% of babies are born on their exact expected due date. A birth is clinically considered "full-term" if it occurs anywhere between 37 weeks and 42 weeks of gestation.