What is IVF transfer day calculation?

For 3-day embryo transfers, EDD = transfer date + 263 days. For 5-day (blastocyst) transfers, EDD = transfer date + 261 days. This accounts for the embryo's age at the time of transfer.

What are the three trimesters?

First trimester: Weeks 1–12. Second trimester: Weeks 13–26. Third trimester: Weeks 27–40. Each trimester has distinct developmental milestones and recommended prenatal checks.

Pregnancy Due Date Calculator — EDD & Week-by-Week Milestones

First Day of Last Menstrual Period (LMP)

Average Cycle Length (days)

Default 28 days. Adjust if your cycle is longer or shorter.

ℹ️ How to use

Choose method — By LMP (most common), Conception Date, or IVF Transfer
Enter the date and adjust cycle length if needed
Click Calculate to see your EDD, current week, and milestone dates

⚠️ This is an estimate. Your doctor may revise the EDD after an early ultrasound. Consult your gynaecologist for medical advice.

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❓ Frequently Asked Questions

How accurate is due date calculation?

Only about 5% of babies are born on their exact due date. The EDD is a statistical estimate — 80% of births occur within 2 weeks before or after the calculated date. Ultrasound scans (especially at 8–12 weeks) can refine the estimate significantly.

What is Naegele's rule?

Naegele's rule is the standard medical formula: EDD = First day of last menstrual period + 280 days (40 weeks). It assumes a 28-day cycle with ovulation on day 14.

Can the due date change?

Yes. The due date may be revised after an early ultrasound (dating scan at 8–12 weeks), which is more accurate than LMP calculation for irregular cycles. Your doctor may update the EDD based on fetal size measurements.

What week is 9 months pregnant?

At 40 weeks (EDD), you are at the end of the 9th month. Full term is 37–42 weeks. Pregnancy is counted in weeks because each month has a different number of days.

What if my cycle isn't 28 days?

If your cycle is longer than 28 days, ovulation occurs later and your EDD is later. For example, a 35-day cycle pushes the EDD one week later. Enter your actual cycle length in the calculator for a more accurate estimate.