Pregnancy Due Date Calculator

What is a Pregnancy Due Date?

A pregnancy due date, also known as the estimated date of delivery (EDD), is the predicted date when a pregnant woman is expected to give birth. This date is calculated to be approximately 280 days (40 weeks) from the first day of the woman's last menstrual period (LMP).

It's important to note that only about 5% of babies are born on their exact due date. Most babies are born between 37 and 42 weeks of pregnancy, which is considered full term. The due date is an estimate and serves as a reference point for tracking the pregnancy's progress and planning prenatal care.

Calculation Methods

• Last Menstrual Period (LMP): The most common method, using Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This method assumes a regular 28-day cycle with ovulation occurring on day 14.
• Conception Date: If you know when conception occurred (or likely occurred), the due date is calculated by adding 266 days (38 weeks) to that date. This method is particularly useful for those who used fertility treatments or know the exact date of conception.
• Ultrasound Dating: The most accurate method, especially when performed in the first trimester (weeks 8-13). The ultrasound measures the size of the fetus to determine gestational age and calculate the due date. This method is often used to confirm or adjust the due date calculated from LMP.

Pregnancy Trimesters

• First Trimester (Weeks 1-13): This period covers conception through week 13. Major organs and structures begin to form. Morning sickness, fatigue, and breast tenderness are common symptoms.
• Second Trimester (Weeks 14-27): Often called the 'golden period' of pregnancy. Energy levels typically improve, morning sickness subsides, and you may start to feel baby's movements. The baby's gender can usually be determined during this time.
• Third Trimester (Weeks 28-40+): The final stretch before birth. The baby gains most of their weight during this period. You may experience increased discomfort, Braxton Hicks contractions, and frequent urination as the baby grows and prepares for birth.

Important Notes

• Only about 5% of babies are born on their exact due date - it's an estimate, not a guarantee
• Full-term pregnancy is considered anywhere between 37 and 42 weeks
• First-time mothers tend to deliver slightly later on average than women who have given birth before
• Ultrasound dating in the first trimester is considered the most accurate method for determining due date
• Your healthcare provider may adjust your due date based on ultrasound measurements and other factors
• Regular prenatal checkups are essential for monitoring both mother and baby's health throughout pregnancy
• Contact your healthcare provider if you experience unusual symptoms, severe pain, bleeding, or decreased fetal movement