Pregnancy Trimester Calculator
Track which trimester you are in and see the start/end dates for each phase.
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Calculation Results
Current Trimester: First Trimester
Week 0
Metrics Analysis
First Trimester EndsSeptember 16, 2026
Second Trimester EndsDecember 23, 2026
Third Trimester EndsMarch 31, 2027
How This Calculator Works
Divides the 280-day gestational timeline into three structured blocks: weeks 1-12, 13-26, and 27-40.
Pregnancy Trimester Calculator — Schedule Milestones
Track your transition dates through the three developmental stages of maternal gestation.
Developing Through Trimesters
The first trimester focuses on organogenesis, the second on rapid anatomical growth, and the third on lung development and preparation for delivery.
Planning Trimester Health Goals
Each trimester introduces distinct health markers, nutritional needs, and clinical screen timings.
Clinical Standard Reference Guideline:
ACOG Pregnancy Division Standards.
Frequently Asked Questions (FAQ)
Q:When does the second trimester start?
The second trimester begins precisely at 13 weeks and 0 days of gestational age.