Pregnancy Calculator
Parse LMP or conception data to normalize gestational age. Validates milestones across trimesters using clinical dating algorithms. View your timeline.
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About Pregnancy Calculator
This pregnancy calculator estimates a due date and timeline from due date, last period, conception date, ultrasound dating, or IVF transfer date. It is for planning and reference only.
How to Use
Choose the dating method and enter the related date.
- Select how the pregnancy should be dated.
- Enter the matching date or ultrasound age.
- Review due date, current status, and trimester milestones.
Examples
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Calculate from last menstrual period
Basis: Last menstrual period Date: 2026-06-01 Estimated conception: 2026-06-15 Second trimester begins: 2026-09-07 Third trimester begins: 2026-12-14 Estimated due date: 2027-03-08
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Calculate from conception date
Basis: Conception date Date: 2026-08-20 Estimated last menstrual period: 2026-08-06 Second trimester begins: 2026-11-12 Third trimester begins: 2027-02-18 Estimated due date: 2027-05-13
Real-World Usage Scenarios
- Clinical Appointment Scheduling - Prenatal Milestones - Identify specific windows for critical prenatal screenings, such as the Nuchal Translucency scan or the 20-week anatomy ultrasound, based on estimated gestational age.
- IVF Due Date Coordination - Embryo Transfer - Convert a 3-day or 5-day embryo transfer date into a standard gestational timeline to align with obstetric dating methods used by midwives and doctors.
- Maternity Leave Preparation - Legal Timelines - Determine the estimated due date to calculate the start of maternity leave and ensure all workplace HR documentation is submitted within the required timeframe.
- Ultrasound Dating Reconciliation - Revised Terms - Compare initial cycle-based estimates with early ultrasound measurements to understand how a clinician might adjust your final delivery window.
Frequently Asked Questions
How does the calculator handle IVF 3-day and 5-day transfers?
For IVF, the pregnancy isn't dated by the last period. A 3-day transfer adds 17 days to the transfer date to find the equivalent 'LMP,' while a 5-day transfer adds 19 days.
Why is the ultrasound date considered more accurate than the last period?
LMP assumes a 28-day cycle with ovulation on day 14. Ultrasound measures the actual size of the embryo or fetus, which accounts for variations in individual ovulation timing.
At what week does the second trimester technically begin?
While definitions vary slightly, the second trimester is generally calculated to begin at the start of week 14, and the third trimester at the start of week 28.
Can I calculate my due date if I have irregular cycles?
If your cycles vary significantly, using the 'Conception Date' or 'Ultrasound Dating' method provides a much more reliable estimate than the 'Last Period' method.
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