The moment you discover you're pregnant, the first question that comes to mind is: 'When will the baby arrive?' While only about 4% of babies are born exactly on their due date, having an Estimated Due Date (EDD) is crucial for monitoring fetal development and planning prenatal care. Our Pregnancy Due Date Calculator uses Naegele's Rule, the gold standard in obstetrics, to provide you with a reliable estimate based on your last menstrual period (LMP) and average cycle length.

Named after Franz Karl Naegele, a German obstetrician who popularized it in the 19th century, Naegele's Rule is a simple yet effective mathematical formula. It assumes that a human pregnancy lasts approximately 280 days (40 weeks) from the first day of the last menstrual period. The formula is: LMP + 7 days - 3 months + 1 year. For example, if your LMP was May 1st, 2025, adding 7 days makes it May 8th. Subtracting 3 months brings it to February 8th, and adding a year gives an EDD of February 8th, 2026.

Standard Naegele's Rule assumes a perfect 28-day menstrual cycle with ovulation occurring on day 14. However, many women have cycles that are longer or shorter. If your cycle is consistently 32 days, you likely ovulated later than day 14, meaning your due date should be adjusted forward by 4 days. Our calculator automatically accounts for these variations, providing a more personalized estimate than basic calendars.

Pregnancy is traditionally divided into three stages, each lasting about 12-14 weeks: 1. First Trimester (Weeks 1-12): A period of rapid development where all major organs begin to form. 2. Second Trimester (Weeks 13-26): Often called the 'honeymoon phase,' as morning sickness usually fades and you begin to feel the baby move. 3. Third Trimester (Weeks 27-40+): The final stretch where the baby grows significantly in size and prepares for life outside the womb.

Beyond the due date, there are several exciting milestones during the 40-week journey. Around week 6, a heartbeat can often be detected via ultrasound. By week 20, you'll have your mid-pregnancy anatomy scan. Week 24 is considered the 'point of viability,' where the baby has a chance of survival if born prematurely. Tracking these dates helps you stay connected to your baby's growth and ensures you're prepared for each stage of prenatal care.