Pregnancy Due Date

The Journey Begins: The Pregnancy Due Date Calculator

A pregnancy due date, or estimated date of delivery (EDD), is a projection of when a pregnant person will likely give birth. While it's called a 'due date', it's important to remember that it's only an estimate. Only about 4-5% of babies are born on their exact due date. However, having an estimated due date is incredibly important for both the expectant parents and their healthcare providers. It provides a timeline for the pregnancy, allowing doctors to track the baby's growth and development, schedule necessary tests and check-ups at the appropriate times, and plan for a safe delivery. For parents, it's a cherished date that helps them prepare emotionally, financially, and logistically for the arrival of their new family member.

This calculator uses Naegele's rule, the most common method for estimating a due date. This rule works by taking the first day of your last menstrual period (LMP), adding one year, subtracting three months, and adding seven days. This calculation is based on the assumption of a regular 28-day menstrual cycle, with ovulation occurring on day 14. For those who know their exact date of conception (for example, through IVF or ovulation tracking), the calculator can also provide an estimate based on that date. By providing a quick and simple way to estimate this important milestone, this tool can help you begin your pregnancy journey with a clearer understanding of your timeline.

How the Due Date is Calculated

The standard methods for estimating a due date are:

• Naegele's Rule (based on LMP): This is the most common method. The formula is:
  Due Date = (First Day of Last Menstrual Period) - 3 Months + 7 Days + 1 Year
  This assumes a 280-day (40-week) gestation period from the LMP.
• Based on Conception Date: If the exact date of conception is known, the due date can be estimated more directly. The average human gestation period is 266 days (38 weeks) from the date of conception.
  Due Date = Conception Date + 266 Days

Understanding Gestational Age

Pregnancy is typically measured in 'gestational weeks' starting from the first day of the last menstrual period, not the date of conception. This means that at the time of conception (around week 2), you are already considered to be 'two weeks pregnant'. A full-term pregnancy is considered to be 40 weeks of gestation.