Pregnancy Due Date Calculator
Calculate your estimated due date (EDD) from LMP, conception date, or IVF transfer date. Track milestones and trimesters.
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About the Pregnancy Due Date Calculator
The estimated due date (EDD) is calculated using Naegele's rule: add 280 days (40 weeks) to the first day of the last menstrual period (LMP). This rule has been standard obstetric practice since the 19th century. About 5% of babies are born on their exact due date; normal delivery range is 37-42 weeks. This calculator also supports IVF transfers and conception-date-based estimates, and displays the full milestone timeline so expectant parents know exactly when to schedule each prenatal visit.
Naegele's Rule for EDD
EDD = LMP + 280 days (40 weeks)
LMP = First day of last menstrual period | IVF 5-day blast: LMP equivalent = Transfer date - 14 days (fresh) or - 17 days (frozen) | Current week = (Today - LMP) / 7
Worked Example
LMP on 1 January 2025, calculating due date
EDD: October 8, 2025 | Gender scan (Wk 16): April 16, 2025 | Anatomy scan (Wk 20): May 14, 2025 | Full term (Wk 39): September 24, 2025
Tips & Insights
- 1
The due date is an estimate - only 5% of babies arrive on the exact date. Dates within 2 weeks either side are medically normal.
- 2
If your cycle is longer than 28 days, your actual ovulation (and conception) happens later, shifting the due date. Ultrasound dating in the first trimester is the most accurate method.
- 3
Week 20 anatomy scan (TIFFA scan) is the most important routine ultrasound - it checks organ development, placenta position, and amniotic fluid.
- 4
Viability milestone is week 24 - babies born after this have a chance of survival with intensive medical care. Survival rates rise sharply with each week after 24.
- 5
Schedule your first trimester screen (NT scan + blood test) between weeks 11-13+6. This is the window for chromosomal screening.
- 6
Most airlines allow pregnant passengers up to 36 weeks. Check airline-specific policies if traveling internationally after 28 weeks.
Why this matters for you
The due date anchors every prenatal appointment, test, and preparation milestone. Missing the NT scan window (weeks 11-13) or the anatomy scan window (weeks 18-22) cannot be undone. For IVF pregnancies, the calculation is different from natural conception and is often misunderstood by patients. Having all milestones visible on one page helps expectant parents plan prenatal care, workplace leave, and hospital bookings without missing critical windows.
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