1. What Is Pregnancy Calculator Last Menstrual Period?

The Pregnancy Calculator based on Last Menstrual Period (LMP) estimates the due date and current gestational age using Naegele's rule. This method calculates the estimated due date by adding 280 days (40 weeks) to the first day of the last menstrual period.

2. How Does The Calculator Work?

The calculator uses the standard obstetric formula:

Where:

• \( EDD \) — Estimated Due Date
• \( LMP \) — Last Menstrual Period (first day)
• \( 280 \text{ days} \) — Standard pregnancy duration (40 weeks)

Explanation: This calculation assumes a regular 28-day menstrual cycle with ovulation occurring on day 14. The method is based on Naegele's rule, which has been used in obstetrics for centuries.

3. Importance Of Due Date Calculation

Details: Accurate due date estimation is crucial for proper prenatal care, monitoring fetal development, scheduling important tests, and preparing for delivery. It helps healthcare providers track pregnancy progress and identify potential complications.

4. Using The Calculator

Tips: Enter the first day of your last menstrual period. Ensure the date is accurate for the most reliable results. The calculator will provide your estimated due date and current gestational age in weeks and days.

5. Frequently Asked Questions (FAQ)

Q1: How Accurate Is The LMP Method?
A: The LMP method is reasonably accurate for women with regular 28-day cycles. For irregular cycles, ultrasound dating in early pregnancy may be more precise.

Q2: What If I Have Irregular Periods?
A: If you have irregular menstrual cycles, the LMP method may be less accurate. An early pregnancy ultrasound (6-12 weeks) provides the most reliable dating.

Q3: Why 280 Days Instead Of 9 Months?
A: Pregnancy is calculated as 40 weeks from LMP, which equals 280 days. This accounts for the fact that conception typically occurs about 2 weeks after LMP.

Q4: Can The Due Date Change?
A: Yes, due dates may be adjusted based on early ultrasound measurements, especially if there's a significant difference from LMP-based calculation.

Q5: What Percentage Of Babies Are Born On Their Due Date?
A: Only about 5% of babies are born exactly on their due date. Most births occur within two weeks before or after the estimated due date.