Calculate your due date, track pregnancy weeks & trimesters, and get personalized updates for your pregnancy journey.
How Pregnancy Dating Works
Pregnancy typically lasts about 40 weeks from the first day of your last menstrual period (LMP) to birth. This is divided into three trimesters:
Pregnancy Timeline:
- First Trimester: Week 1 to Week 12
- Second Trimester: Week 13 to Week 26
- Third Trimester: Week 27 to Birth
Key Pregnancy Milestones
First Trimester (Weeks 1-12)
- Positive pregnancy test (week 4-5)
- First ultrasound (week 6-8)
- Heartbeat detectable (week 6-7)
- Morning sickness peaks (week 9-10)
Second Trimester (Weeks 13-26)
- Gender reveal possible (week 16-20)
- Quickening (first fetal movements, week 18-22)
- Anatomy scan (week 20)
- Most comfortable trimester
Third Trimester (Weeks 27-40)
- Fetal viability (week 24+)
- Regular fetal movements
- Braxton Hicks contractions
- Baby drops (lightening, week 36-40)
Pregnancy Week-by-Week
Select a week to learn about your baby's development:
Week 1-4
Conception & implantation
Week 5-8
Organ formation begins
Week 9-12
Fetal movement starts
Week 13-16
Gender development
Week 17-20
Quickening occurs
Week 21-24
Viability reached
Week 25-28
Lung development
Week 29-32
Rapid brain growth
Week 33-36
Fat accumulation
Week 37-40
Full term
Due Date Accuracy
Only about 5% of women deliver on their exact due date. Most babies are born within two weeks before or after:
| Time Frame |
Percentage of Births |
| 2 weeks early to 1 week early |
30% |
| 1 week early to due date |
25% |
| Due date to 1 week late |
25% |
| 1-2 weeks late |
15% |
| More than 2 weeks late |
5% |
Note: Your healthcare provider may adjust your due date based on ultrasound measurements, especially if they differ significantly from your LMP date.
Pregnancy Health Tips
First Trimester
- Start prenatal vitamins with folic acid
- Manage morning sickness with small, frequent meals
- Avoid alcohol, tobacco, and unnecessary medications
- Schedule your first prenatal visit
Second Trimester
- Begin maternity clothes as needed
- Start prenatal exercises (with doctor's approval)
- Monitor weight gain (1 lb/week recommended)
- Consider childbirth education classes
Third Trimester
- Prepare baby essentials and hospital bag
- Practice relaxation and breathing techniques
- Monitor fetal movement patterns
- Finalize birth plan with healthcare provider
Frequently Asked Questions
Q: Why is pregnancy calculated from last period if conception happens later?
A: The last menstrual period (LMP) is used because it's a definite date most women can recall, while conception date is often uncertain. Pregnancy is calculated as 40 weeks from LMP, which is about 38 weeks from conception.
Q: Can my due date change?
A: Yes, especially if early ultrasound measurements differ from your LMP date by more than 5-7 days. Later ultrasounds are less accurate for dating.
Q: Is it safe to go past my due date?
A: Most providers allow pregnancy to continue until 41-42 weeks with monitoring. After 42 weeks, risks increase and induction is usually recommended.
Q: How accurate are conception calculators?
A: Conception date calculators are estimates. Conception typically occurs 11-21 days after the first day of your last period, depending on cycle length.
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