Enter the first day of your last period to find your due date, gestational age, trimester, and upcoming pregnancy milestones. Adjusts for cycle length.
| Week | Date | Milestone |
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Your due date is the most anticipated date in pregnancy, yet only 5% of babies arrive on it. Understanding how due dates are calculated, what the milestones mean, and what to expect each trimester helps you prepare and reduces anxiety. This guide covers the science behind due date calculation, the key milestones you will encounter, and practical preparation tips.
Scenario 1: Standard 28-Day Cycle. Maria’s LMP was February 6. Due date: February 6 + 280 days = November 13, 2026. She is currently 10 weeks along (trimester 1). Morning sickness is easing. First ultrasound confirmed viability at week 8. Anatomy scan scheduled for week 20 (late June). Use our Macros for Pregnancy Calculator for nutrition targets.
Scenario 2: Long Cycle (35 days). Sarah has a 35-day cycle with LMP January 15. Standard calculation: October 22. With cycle adjustment (+7 days): October 29, 2026. Without the adjustment, she would think she is a week further along than she actually is. The 7-day shift matters for accurate milestone tracking.
Scenario 3: Ultrasound Changes Due Date. Priya’s LMP gave a due date of December 1. Her 8-week ultrasound measured the baby at 7 weeks, 2 days. Her doctor adjusted the due date to December 6. First-trimester ultrasound is accurate to within 5-7 days and takes priority over LMP calculation if there is more than a 7-day difference.
Scenario 4: First-Time Mother. David and Lisa are expecting their first baby, due September 20. First-time mothers go an average of 5 days past due. Realistic range: September 6 to October 4 (38-42 weeks). They pack the hospital bag at week 35 and start weekly doctor visits at week 36. Only 4-5% of babies arrive on the exact due date.
💡 Key insight: The due date is a 5-week window, not a single day. Full term is 37-42 weeks. Babies born between 39-41 weeks have the best outcomes. Do not stress about the exact date. Focus on reaching full term (37 weeks), and think of your due date as the center of a range, not a deadline.
| 1st Trimester | Weeks 1-12 |
| 2nd Trimester | Weeks 13-26 |
| 3rd Trimester | Weeks 27-40 |
| Viability | Week 24 |
| Full Term | Week 37+ |