🤰 Pregnancy Due Date Calculator

EDD = LMP + 280 days (40 weeks) More precisely for non-28-day cycles: EDD = LMP + 280 + (Cycle Length − 28) days Example: LMP = Jan 1, cycle = 30 days EDD = Jan 1 + 280 + 2 = Oct 11 Based on the observation that pregnancy lasts approximately 280 days (40 weeks) from the LMP for a 28-day cycle.

EDD = Conception Date + 266 days (38 weeks) Conception typically occurs ~14 days after LMP (at ovulation in a 28-day cycle) 266 days from conception = 280 days from LMP Both methods give the same EDD for a 28-day cycle.

EDD = Ultrasound Date + (280 − Gestational Age days) Gestational Age days = weeks × 7 + extra days Most accurate in the first trimester (before 13w6d) Crown-Rump Length (CRL) is measured in 1st trimester Biparietal Diameter (BPD) used in 2nd trimester 1st trimester ultrasound: accurate to ±5 days 2nd trimester: accurate to ±10-14 days 3rd trimester: accurate to ±3 weeks

Day 5 transfer (blastocyst): EDD = Transfer Date + 261 days (Because embryo is already 5 days old) Day 3 transfer (cleavage): EDD = Transfer Date + 263 days Day 6 transfer: EDD = Transfer Date + 260 days IVF dating is the most precise method since the exact fertilisation date is known.

First Trimester: Week 1 — Week 12 (Weeks 1–13) Second Trimester: Week 13 — Week 26 (Weeks 14–27) Third Trimester: Week 27 — Week 40 (Weeks 28–40+) Full Term: Week 37 — Week 42 Preterm: Before Week 37 Post-term: After Week 42 Normal delivery window: 38–42 weeks