Pregnancy Due Dates Calculator
Pregnancy Due Date (Naegele)
Gestational Age:
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weeks/days
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Calculates pregnancy dates from last period, gestational age, or date of conception.
Why Use
Accurate estimates of gestational age may positively affect pregnancy outcomes, including lower risk of post-term induction and earlier detection of multiple gestations ( Whitworth 2015 ).
When to Use
Patients who are pregnant or may be pregnant.
Formula
Estimated gestational age (EGA) = time since 1 st day of last menstrual period (LMP) Estimated date of conception (EDC) = two weeks* since 1 st day of LMP Estimated due date (EDD) = 1 st day of LMP + 40 weeks* (Naegele's Rule) *Assumes 28 day cycle. If cycle is longer than 28 days, this calculator adds the number of days more than 28 to obtain EDD. Example: if cycle length is 35 days, add 7 days (= 35 – 28) to 40 weeks.
Pearls / Pitfalls
According to ACOG , ultrasound measurement in the first trimester (up to and including 13 6/7 weeks of gestation) is the most accurate method to establish or confirm gestational age.
Advice
Use to track and estimate pregnancy.