How do you calculate due date from frozen embryo transfer?

For FET due date calculation, subtract the embryo age from the transfer date to find your 'adjusted LMP,' then add 280 days (40 weeks). For a Day 5 embryo: transfer date minus 19 days equals adjusted LMP. For Day 3: transfer date minus 17 days. For Day 6: transfer date minus 20 days. This accounts for the embryo's development before transfer.

Is FET due date different from natural conception due date?

FET due dates are calculated differently but result in the same 40-week pregnancy. Natural conception uses last menstrual period (LMP), but FET uses the transfer date adjusted for embryo age. FET due dates are often more accurate because the exact conception/fertilization date is known, unlike natural conception where ovulation timing varies.

What is the difference between Day 3 and Day 5 embryo transfer due dates?

The due date calculation differs by embryo development stage. Day 5 embryos (blastocysts) are 5 days post-fertilization, so you subtract 19 days from transfer to find adjusted LMP. Day 3 embryos subtract 17 days. Day 6 blastocysts subtract 20 days. The final due date will be the same gestational age regardless of transfer day.

How accurate are FET due date calculations?

FET due dates are among the most accurate because fertilization date is precisely known. However, only about 5% of babies arrive on their due date. Most full-term babies arrive within 2 weeks before or after the due date (38-42 weeks). First pregnancies often go past the due date, while subsequent pregnancies may deliver earlier.

What are the key pregnancy milestones after frozen embryo transfer?

Key FET milestones: Beta HCG blood test at 9-12 days post-transfer, first ultrasound at 6-7 weeks to confirm heartbeat, end of first trimester at 12-13 weeks, anatomy scan at 18-22 weeks, viability milestone at 24 weeks, third trimester at 28 weeks, full term at 37 weeks, and due date at 40 weeks from adjusted LMP.

When do you stop progesterone after FET pregnancy?

Most IVF clinics continue progesterone support until 8-12 weeks of pregnancy when the placenta takes over hormone production. Some clinics extend to 12 weeks for extra caution. Your fertility doctor will advise when to stop based on your hormone levels and ultrasound findings. Never stop progesterone without consulting your medical team.

FET Due Date Calculator

Calculate your due date from frozen embryo transfer with pregnancy milestones for IVF pregnancies

Last updated: June 2026

Embryo Transfer Date

The date of your FET procedure

Embryo Day at Transfer

Most FETs use Day 5 or 6 blastocysts

Common Questions

How is FET due date calculated?

For frozen embryo transfers, we know the exact conception date. We subtract the embryo age (3, 5, or 6 days) from transfer date to get conception, then subtract 14 more days to get your "last menstrual period" (LMP). Your due date is 280 days from that LMP date.

Is FET dating accurate?

Yes, FET due date calculations are highly accurate because we know the exact conception date. Unlike natural pregnancy where ovulation is estimated, with FET we know precisely when the embryo was created. However, actual delivery can vary by ±2 weeks from the due date.

Do Day 3 and Day 5 transfers have different due dates?

Yes, Day 5 embryo transfers result in a due date 2 days earlier than Day 3 transfers because the embryo is already 5 days old at transfer (vs 3 days old). This means your pregnancy is technically "further along" with a Day 5 transfer.

How long do I continue progesterone after FET?

Most clinics continue progesterone supplementation until 10-12 weeks of pregnancy, when the placenta takes over progesterone production. Never stop medications without your doctor's approval, as stopping too early can risk pregnancy loss.

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FET Due Date Calculator

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