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Digital obstetric wheel for due date, gestational age, and pregnancy milestones.

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[ about ]

The OB Wheel Calculator is a comprehensive online tool designed for obstetricians, midwives, and general practitioners to calculate gestational age and estimated due date (EDD) from the last menstrual period (LMP). It applies Naegele's Rule: EDD = LMP + 280 days, with adjustment for non-standard cycle lengths. This digital OB wheel replicates the physical wheel and extends it with reference data, including expected fetal biometry (CRL, BPD, HC, AC, FL) and approximate weight for the calculated gestational age, as well as the full antenatal test schedule, trimester-wise precautions, and a quantitative β-hCG dating chart.

Key Features:

  • Due Date (EDD): Calculate the estimated due date based on LMP and cycle length.
  • Gestational Age: Determine the current gestational age in weeks and days.
  • Scan Dating: Back-calculate EDD from ultrasound dating.
  • IVF Milestones: Calculate precise due date and gestational age for pregnancies achieved through assisted reproductive technology (ART).
  • GA on Date: Find exact gestational age on a specific date for documentation purposes.
  • Reverse Pregnancy Wheel: Calculate LMP and conception date when only the EDD is known.

Additional Resources:

  • Prenatal Test Schedule: Access a trimester-wise schedule of recommended prenatal tests and screenings.

  • β-hCG Chart: Utilize a quantitative β-hCG dating guide for early pregnancy assessment.

  • Fetal Biometry: Reference expected fetal biometry values (CRL, BPD, HC, AC, FL) by gestational week. Due date calculator Clinical References & Practice Guidelines:

  • American College of Obstetricians and Gynecologists (ACOG). Committee Opinion No. 700: Methods for Estimating the Due Date. Obstet Gynecol. 2017;129(5):e150–e154.

  • Hadlock FP, Harrist RB, Deter RL, Park SK. Estimating fetal age: computer-assisted analysis of multiple fetal growth parameters. Radiology. 1984;152(2):497–501.

  • Federation of Obstetric and Gynaecological Societies of India (FOGSI). Clinical Practice Guidelines on Antenatal Care & GDM Screening in India. 2021.

  • World Health Organization (WHO). WHO recommendations on antenatal care for a positive pregnancy experience. Geneva: World Health Organization; 2016.