Pregnancy Due Date Calculator
Calculate your estimated due date based on your last menstrual period, conception date, IVF transfer, or ultrasound.
Calculation Method
Date
Cycle Length
Key Milestones
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How Is Your Due Date Calculated?
Your estimated due date (EDD) is typically calculated using Naegele's Rule:
This assumes:
- A 28-day menstrual cycle
- Ovulation occurred on day 14
Only about 5% of babies are born on their actual due date. Most arrive within two weeks before or after.
Calculation Methods
Last Menstrual Period (LMP)
- Most common method
- Based on first day of your last period
- Adjusted for cycle length if different from 28 days
Conception Date
- If you know when you conceived
- Adds 266 days (38 weeks)
IVF Transfer
- For 5-day blastocyst: adds 261 days
- For 3-day embryo: adds 263 days
Ultrasound Dating
- Most accurate in first trimester
- Measures crown-rump length
Pregnancy Timeline
| Trimester | Weeks | Key Events |
|---|---|---|
| First | 1-12 | Organ formation, morning sickness |
| Second | 13-26 | Baby movements felt, anatomy scan |
| Third | 27-40 | Rapid growth, preparation for birth |
Key Milestones
- Week 12: End of first trimester, lower miscarriage risk
- Week 20: Halfway point, anatomy ultrasound
- Week 24: Viability milestone
- Week 28: Third trimester begins
- Week 37: Considered full term
- Week 40: Due date
Accuracy of Due Dates
Due date estimates have varying accuracy:
- First trimester ultrasound: ± 5 days
- LMP calculation: ± 2 weeks
- Second trimester ultrasound: ± 1-2 weeks
Your healthcare provider may adjust your due date based on ultrasound measurements.