Pregnancy Due Date Calculator

Pregnancy Due Date is evaluated from Calculate From, Date and Average Cycle Length - LMP only. The calculation reports Estimated Due Date, Estimated Conception Date and Current Gestational Age.

Results

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About the Pregnancy Due Date Calculator

Pregnancy Due Date is treated here as a quantitative relation between Calculate From, Date and Average Cycle Length - LMP only and Estimated Due Date, Estimated Conception Date and Current Gestational Age.

The calculator uses a multi formula configuration. Each reported value is read as a direct evaluation of the stored rules with the declared field formats and units.

Formula basis:
EDD = LMP + 280 days + cycle adjustment
Cycle adjustment = Cycle Length - 28 days
Conception estimate = LMP + 14 days + cycle adjustment
EDD = Conception Date + 266 days
LMP estimate = Conception Date - 14 days

Interpret the outputs in the order shown by the result fields. Optional inputs affect only the outputs that depend on those variables.

Formula & How It Works

The calculation applies the following relations exactly as recorded in the metadata:

EDD = LMP + 280 days + cycle adjustment
Cycle adjustment = Cycle Length - 28 days
Conception estimate = LMP + 14 days + cycle adjustment
EDD = Conception Date + 266 days
LMP estimate = Conception Date - 14 days

Each output field is produced by substituting the supplied inputs into the relevant relation and then applying the declared rounding or text format.

Worked Examples

Example 1: Standard 28-Day Cycle from LMP

Inputs

input_method: lmp start_date: 2024-01-15 cycle_length: 28
Estimated Due Date: 2024-10-21. Estimated Conception Date: 2024-01-29. Current Gestational Age: 120 weeks, 3 days

With Calculate From = lmp, Date = 2024-01-15 and Average Cycle Length - LMP only = 28 as the stated inputs, the result is Estimated Due Date = 2024-10-21, Estimated Conception Date = 2024-01-29 and Current Gestational Age = 120 weeks, 3 days. Each value corresponds to the declared output fields.

Example 2: Longer Cycle — 35 Days

Inputs

input_method: lmp start_date: 2024-02-01 cycle_length: 35
Estimated Due Date: 2024-11-14. Estimated Conception Date: 2024-02-22. Current Gestational Age: 118 weeks, 0 days

With Calculate From = lmp, Date = 2024-02-01 and Average Cycle Length - LMP only = 35 as the stated inputs, the result is Estimated Due Date = 2024-11-14, Estimated Conception Date = 2024-02-22 and Current Gestational Age = 118 weeks, 0 days. Each value corresponds to the declared output fields.

Example 3: From Known Conception Date

Inputs

input_method: conception start_date: 2024-03-10
Estimated Due Date: 2024-12-01. Estimated Conception Date: 2024-03-10. Current Gestational Age: 114 weeks, 4 days

With Calculate From = conception and Date = 2024-03-10 as the stated inputs, the result is Estimated Due Date = 2024-12-01, Estimated Conception Date = 2024-03-10 and Current Gestational Age = 114 weeks, 4 days. Each value corresponds to the declared output fields.

Example 4: Checking Current Gestational Age

Inputs

input_method: lmp start_date: 2024-05-20 cycle_length: 28
Estimated Due Date: 2025-02-24. Estimated Conception Date: 2024-06-03. Current Gestational Age: 102 weeks, 3 days

With Calculate From = lmp, Date = 2024-05-20 and Average Cycle Length - LMP only = 28 as the stated inputs, the result is Estimated Due Date = 2025-02-24, Estimated Conception Date = 2024-06-03 and Current Gestational Age = 102 weeks, 3 days. Each value corresponds to the declared output fields.

Common Use Cases

  • Calculate estimated due date from last menstrual period
  • Find due date from known conception date
  • Calculate current gestational age
  • Plan prenatal care appointments