Pregnancy Date Calculator

What is a Pregnancy Date Calculator?

A Pregnancy Date Calculator is a tool used to estimate important dates and milestones during pregnancy. It typically calculates the due date, conception date, and the beginning of each trimester based on either the first day of the last menstrual period (LMP) or a known due date.

How Pregnancy Dates are Calculated

Pregnancy dates are typically calculated using Naegele's rule, which assumes:

• An average menstrual cycle of 28 days
• Ovulation occurs on day 14 of the cycle
• Pregnancy lasts approximately 280 days (40 weeks) from the start of the last menstrual period

Key Formulas

1. Due Date = LMP + 280 days
2. Conception Date ≈ LMP + 14 days
3. 2nd Trimester Start = Conception Date + 13 weeks
4. 3rd Trimester Start = Conception Date + 26 weeks

Example Calculation

Let's calculate pregnancy dates for a woman whose last menstrual period started on May 1, 2023:

1. LMP: May 1, 2023
2. Conception Date: May 15, 2023 (LMP + 14 days)
3. Due Date: February 5, 2024 (LMP + 280 days)
4. 2nd Trimester Start: August 14, 2023 (Conception + 13 weeks)
5. 3rd Trimester Start: November 13, 2023 (Conception + 26 weeks)

Visual Representation

This timeline represents the key dates in our example pregnancy calculation.