The EDD (Estimated Date of Delivery) Calculator is a sophisticated pregnancy dating tool that helps expectant mothers and healthcare providers accurately determine pregnancy due dates and track gestational age. It uses multiple clinically validated methods including Last Menstrual Period (LMP), conception date, and ultrasound dating to provide the most accurate pregnancy timeline. This calculator is essential for prenatal care planning, ultrasound scheduling, and monitoring fetal development.
The Foundation: Pregnancy Dating Methods
Pregnancy dating can be calculated using three primary methods, each with different levels of accuracy. The Last Menstrual Period (LMP) method is the most commonly used and adds 280 days (40 weeks) to the first day of the last menstrual period. The conception date method adds 266 days (38 weeks) to the known conception date, providing the most accurate estimated date of delivery. Ultrasound dating uses fetal measurements to determine gestational age and calculate the delivery date.
Gestational Age and Pregnancy Timeline
Gestational age is measured from the first day of the last menstrual period, not from conception. A full-term pregnancy is 40 weeks (280 days) from LMP, but only 38 weeks (266 days) from conception. The calculator tracks current gestational age, weeks remaining until delivery, and important pregnancy milestones like trimester boundaries. Understanding gestational age is crucial for monitoring fetal development and scheduling prenatal care.
Accuracy and Clinical Validation
The accuracy of estimated date of delivery calculation depends on the method used and individual factors. LMP dating assumes a 28-day cycle with ovulation on day 14, but many women have different cycle lengths. Conception date dating is most accurate but requires knowing the exact conception date. Ultrasound dating in the first trimester is highly accurate and can correct LMP dates by up to 7 days.