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OB Wheel / EDD Calculator

Calculate Expected Delivery Date from LMP or ultrasound gestational age. View pregnancy timeline and key milestone dates.

📅 Last Menstrual Period (LMP)
EDD = LMP + 280 days (Naegele's Rule). Assumes 28-day cycle.
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Enter dates and calculate
Select LMP date or ultrasound GA to calculate EDD, gestational age, trimester, and pregnancy timeline.
Obstetric Dating

How the Digital OB Wheel Works

Calculate pregnancy milestones and due dates with Naegele's rule or ultrasound biometry.

1
Select Dating Method
Choose between dating by Last Menstrual Period (LMP) or dating by a First-Trimester Dating Ultrasound (USG).
2
Input Date & Gestational Age
Enter the first day of the LMP, or the ultrasound date along with the sonographic gestational age in weeks and days.
3
Determine EDD & Trimester
The tool calculates the Estimated Date of Delivery (EDD = LMP + 280 days), current weeks + days, and exact trimester phase.
4
Review Antenatal Calendar
Inspect key scheduled milestones including Nuchal Translucency (NT) scan, Anomaly TIFFA scan, Glucose Tolerance, and Full Term (37 weeks).
Gynecology & ANC

Why Obstetricians Love ClinicKare OB Wheel

Eliminates inaccurate plastic spinning wheels with instantaneous, calendar-accurate dating.

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Calendar Day Precision
Calculates exact pregnancy chronologies without leap-year or month-length errors common to mechanical cardboard discs.
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Ultrasound Back-Calculation
Handles irregular cycles effortlessly by back-calculating true gestational age and clinical EDD from crown-rump length (CRL) dating scans.
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Visual 40-Week Timeline
Interactive progress bar visually portrays the pregnancy journey through First, Second, and Third Trimesters up to 40 weeks.
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Key Antenatal Scan Windows
Instantly generates target calendar dates for crucial investigations (11-13 week NT scan, 18-20 week anomaly scan, 24-28 week OGTT).
Antenatal FAQ OB Wheel FAQ

Frequently Asked Questions

Answers to common questions about using the OB wheel and pregnancy due date calculator.

Q What is Naegele's rule for calculating EDD?

Naegele's rule calculates the Estimated Date of Delivery by taking the first day of the Last Menstrual Period (LMP), adding 1 year, subtracting 3 months, and adding 7 days (standard 280-day gestation).

Q How do I switch between LMP date and Ultrasound scan calculation modes?

Use the toggle button at the top of the calculator to switch between "Last Menstrual Period (LMP)" mode and "Ultrasound Dating" mode. In Ultrasound mode, enter the scan date and gestational age in weeks and days to calculate the adjusted EDD.

Q What pregnancy milestones are displayed in the timeline?

The tool charts key clinical milestones including the end of the 1st Trimester (13w), NT scan window (11-13w), Anomaly/TIFFA scan window (18-20w), fetal viability (24w), 3rd Trimester start (28w), full term window (37w), and Estimated Date of Delivery (40w).

Q When is a pregnancy officially considered full term?

A pregnancy is clinically categorized as Early Term from 37 weeks 0 days to 38 weeks 6 days, Full Term from 39 weeks 0 days to 40 weeks 6 days, and Late Term from 41 weeks 0 days to 41 weeks 6 days.

Obstetrics practice? ClinicKare includes ANC tracker, OB wheel, patient history, and gynecology EMR templates.
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