FET Due Date Calculator

Example Data Table

Formula Used

Standard pregnancy dating uses 280 days from the last menstrual period. It also equals about 266 days from fertilization. In a frozen embryo transfer, embryo development age is already known.

• Gestational age at transfer: 14 days + embryo age
• Estimated fertilization date: transfer date − embryo age
• Equivalent last period date: estimated fertilization date − 14 days
• Estimated due date: transfer date + (266 − embryo age) days
• Gestational age on selected date: selected date − equivalent last period date

For a day 5 blastocyst, the estimated due date is transfer date plus 261 days. For a day 3 embryo, it is transfer date plus 263 days.

How To Use This Calculator

1. Enter the exact frozen embryo transfer date from your clinic.
2. Select the embryo age, such as day 3, day 5, day 6, or day 7.
3. Choose the date used to check current gestational age.
4. Enter the expected blood test timing after transfer.
5. Add embryo count, cycle type, and optional notes.
6. Press the calculate button to view the result above the form.
7. Use CSV or PDF downloads for simple record keeping.
8. Confirm all medical dates with your fertility specialist.

FET Due Date Planning Guide

Understanding FET Due Date Estimates

A frozen embryo transfer due date starts with the transfer day. It also uses the embryo age. This method differs from a natural cycle estimate. In natural timing, the last period often starts the count. In FET care, the embryo already has known development time. That makes the transfer date very useful.

Why Embryo Age Matters

A day three embryo has grown for three days. A day five blastocyst has grown longer. The calculator subtracts that known age from a standard pregnancy length. Pregnancy is often counted as 280 days from the last period. It is also about 266 days from fertilization. The embryo age helps connect both views.

Planning With Milestones

The result gives more than one date. It shows an estimated fertilization date. It also shows an equivalent period date. These dates help you understand gestational age. The tool also lists beta testing, trimester changes, anatomy scan timing, and full term timing. Clinics may schedule these visits differently. Always follow your care team first.

Using Results Wisely

FET pregnancies can include medicated, natural, or modified natural cycles. The due date math is usually the same. Yet clinical decisions can vary. Bleeding, pain, uncertain dates, or unusual results need medical guidance. The calculator is for planning and education. It is not a diagnosis.

For patients tracking several transfers, consistent inputs help. Use the exact transfer date from the clinic. Choose the embryo stage confirmed by the embryology report. Then save the result for later review. The CSV file can support records. The PDF can help during appointment planning.

Helpful Notes For Care

The estimated due date is a planning marker. Many babies arrive before or after that day. Multiple pregnancies may need closer monitoring. Prior medical history can also affect timing. Your clinician may adjust appointments after ultrasound findings. Early scans can confirm location, heartbeat, and growth. Later scans can check anatomy and growth trends.

This calculator keeps the process clear. It turns one transfer date into a full timeline. Use it to prepare questions. Keep all final choices with your fertility clinic.

If dates differ from your chart, ask your clinic which date should guide your records, reminders, and upcoming care plans safely.

FAQs