Pregnancy Calculator
Last Period
Conception Date
Ultrasound Date
About Pregnancy Calculations
Pregnancy is typically calculated from the first day of your last menstrual period (LMP), which is about 2 weeks before conception actually occurs. A full-term pregnancy is about 40 weeks (280 days) from the LMP.
Pregnancy Trimesters:
| Trimester | Weeks | Key Developments |
|---|---|---|
| First | 1-12 | Organ formation, positive pregnancy test |
| Second | 13-27 | Fetal movement, gender visible on ultrasound |
| Third | 28-40 | Rapid growth, preparation for birth |
Important Notes:
- Only about 5% of women deliver on their exact due date
- Most babies are born within 2 weeks before or after the due date
- Ultrasound measurements are most accurate early in pregnancy
- Consult with your healthcare provider for personalized information
Common Pregnancy Milestones:
- Positive pregnancy test: 4-5 weeks
- First ultrasound: 8-12 weeks
- Fetal movement felt: 16-25 weeks
- Viability (chance of survival if born): 24 weeks