Due Date Calculator
Articles, guides, and in-depth tips for the Due Date Calculator — everything you need to get the most out of it.
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Why Your 40-Week Due Date Is Actually 38 Weeks of Pregnancy — Ultrasound Dating, Naegele's Rule, and When Induction Is Recommended
Why Pregnancy Is Counted From Before It Began — The LMP Convention, Gestational Age, and Why Your App Says You're Further Along Than You Think
Gestational age is counted from the last menstrual period — not conception — which means a "6-week pregnancy" is about 4 weeks post-conception, and "40 weeks" includes approximately 2 weeks before fertilization. Here's why different calculators give different due dates (cycle length adjustments, ultrasound overrides), what "39+4 weeks" notation means and why the days portion matters clinically, and why Naegele's 280-day rule may slightly underestimate the average first pregnancy duration.
Planning Leave Around Your Due Date: Why "Count Back From the Due Date" Is Just the Starting Point
"My due date is March 15th" doesn't directly answer "when should I start my leave" — leave planning means working backward from an estimated date, applying jurisdiction-specific policies, and building in a buffer for the very real possibility of early arrival. Here's why most leave frameworks let leave begin automatically upon birth regardless of the planned date, why work-handover targets should sit several weeks before the planned leave-start date, and why partner/co-parent leave planning is inherently date-range-based rather than fixed.
Twin Pregnancy Due Dates, Chorionicity, and IVF Dating: How Multiple Pregnancies Differ
Twin pregnancies average 36-37 weeks rather than 40 — meaning a standard due date calculation represents a date most twin pregnancies won't reach. Here's why multiples arrive earlier, how chorionicity affects monitoring and timing, why IVF dating from embryo transfer is the most precise method available, and what vanishing twin syndrome means for dating.
How Due Dates Are Calculated — And Why Most Babies Don't Arrive on Them
Only 4–5% of babies are born on their due date. Here's how the 40-week calculation works, why it's imprecise, what "term" actually means, and the real distribution of when babies arrive.
Pregnancy Trimesters: Key Milestones, Screening Tests, and Nutritional Priorities Each Stage
The three trimesters represent distinct developmental phases — all major organs form in the first, growth accelerates in the second, and lung maturation dominates the third. Here's a week-by-week guide to key milestones, screening tests by trimester, and specific nutritional priorities at each stage.
Due Date Calculator — Find Your Estimated Due Date & Pregnancy Milestones
Learn how pregnancy due dates are calculated using Naegele's Rule, what the trimester milestones are, how accurate EDD estimates really are, and how to track your pregnancy week by week.
