1. What is the Perinatal Due Date Calculator?

The Perinatal Due Date Calculator estimates the expected delivery date based on the first day of the last menstrual period (LMP) using Naegele's rule, which adds 280 days (40 weeks) to the LMP.

2. How Does the Calculator Work?

The calculator uses the standard obstetric formula:

Where:

• LMP — First day of last menstrual period
• 280 days — Equivalent to 40 weeks gestation

Explanation: This calculation assumes a regular 28-day menstrual cycle with ovulation occurring on day 14. The calculator also shows current gestational age based on today's date.

3. Importance of Due Date Calculation

Details: Accurate due date estimation is crucial for proper prenatal care, timing of tests, and monitoring fetal development. It helps identify preterm or post-term pregnancies that may need intervention.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the format YYYY-MM-DD. The calculator will display your estimated due date and current gestational age.

5. Frequently Asked Questions (FAQ)

Q1: What if my cycles aren't regular?
A: This calculation works best for women with regular 28-day cycles. If your cycles are longer/shorter or irregular, an ultrasound dating scan may be more accurate.

Q2: How accurate is this calculation?
A: Only about 5% of women deliver on their exact due date. Most deliver within 2 weeks before or after the estimated date.

Q3: What if I don't know my LMP?
A: An early pregnancy ultrasound (first trimester) can provide an accurate due date estimation based on fetal measurements.

Q4: Why 280 days?
A: Pregnancy is traditionally calculated as 40 weeks from LMP, though actual conception typically occurs about 2 weeks later in a 28-day cycle.

Q5: Does this account for leap years?
A: Yes, the calculator automatically accounts for leap years in the date calculation.