Pregnancy Calculator
Calculate your due date, current pregnancy week, trimester information, and important milestones. Track your pregnancy journey with accurate dates and developmental stages.
Pregnancy Information
Enter the first day of your last menstrual period
Most women have cycles between 21-35 days. Average is 28 days.
Pregnancy Timeline
Trimester Breakdown
First Trimester
Weeks 1-12
Key developments:
- Major organs form
- Heart starts beating
- Neural tube develops
- Limbs begin to form
Common symptoms: Morning sickness, fatigue, breast tenderness
Second Trimester
Weeks 13-26
Key developments:
- Rapid growth period
- Sex can be determined
- Movement felt
- Hair and nails grow
Common symptoms: Energy returns, baby bump shows, back pain
Third Trimester
Weeks 27-40
Key developments:
- Lungs mature
- Brain develops rapidly
- Weight gain accelerates
- Preparation for birth
Common symptoms: Shortness of breath, frequent urination, Braxton Hicks
Important Pregnancy Milestones
Missed Period
First sign of pregnancy for most women with regular cycles
Heartbeat Detectable
Baby's heart begins beating and may be detected via ultrasound
First Prenatal Visit
Recommended time for first prenatal appointment
End of First Trimester
Risk of miscarriage significantly decreases
Gender Determination
Baby's sex can typically be determined via ultrasound
Anatomy Scan
Detailed ultrasound to check baby's development
Viability Milestone
Baby has a chance of survival if born prematurely
Third Trimester Begins
Final stretch of pregnancy begins
Rapid Brain Development
Baby's brain develops rapidly during this period
Considered Full-Term Soon
Baby is nearly ready for birth
Full-Term
Baby is considered full-term and ready for birth
How Pregnancy Calculation Works
Naegele's Rule
The most common method for calculating due dates is Naegele's Rule, which adds 280 days (40 weeks) to the first day of your last menstrual period (LMP).
Formula: LMP + 280 days = Due Date
Conception Date Method
If you know the conception date, add 266 days (38 weeks) to calculate the due date. This method accounts for the 2-week difference between LMP and actual conception.
Formula: Conception Date + 266 days = Due Date
Important Notes
- Only about 5% of babies are born on their exact due date
- Most babies are born within 2 weeks before or after the due date
- First pregnancies tend to go slightly longer than subsequent pregnancies
- Ultrasound dating may be more accurate, especially in early pregnancy
Example Calculation
Last Menstrual Period: January 1, 2024
Calculation Steps:
1. LMP Date: January 1, 2024
2. Add 280 days (40 weeks)
3. Due Date: October 7, 2024
4. Conception Date: ~January 15, 2024
Timeline (if today is June 1, 2024):
• Current week: 22 weeks, 1 day
• Days pregnant: 152 days
• Trimester: Second
• Days remaining: 128 days
Frequently Asked Questions
How accurate are pregnancy calculators?
Pregnancy calculators provide estimates based on average pregnancy length. They're most accurate when based on a reliable LMP date or early ultrasound. Only about 5% of babies are born on their exact due date.
What if I have irregular periods?
If you have irregular periods, the LMP method may be less accurate. In this case, early ultrasound dating (between 8-13 weeks) is typically more reliable for determining your due date.
When should I see a healthcare provider?
Schedule your first prenatal appointment as soon as you confirm pregnancy, ideally between 6-8 weeks. Early prenatal care is important for monitoring both maternal and fetal health.
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