This calculator follows standard obstetric formulas used by fertility specialists and OB/GYNs. It assumes a 40-week (280-day) pregnancy when calculated from the first day of your last menstrual period (LMP). For IVF cycles, it adjusts automatically: Day-3 transfer adds 263 days and Day-5 transfer adds 261 days. Your actual due date may be adjusted by your doctor based on early ultrasound measurements.
IVF & Surrogacy Due Date Calculator
Due Date Calculator for Surrogacy
Calculate your estimated due date using LMP, Day-3 embryo transfer, or Day-5 blastocyst transfer. View trimester ranges, key milestones, and track pregnancy progress.
Due Date Calculator
Choose your method, select the date (Month / Day / Year), then calculate. Supports natural conception/IUI and IVF transfers (Day-3 or Day-5).
Assumptions: LMP → 280 days (40 weeks). IVF Day-3 → transfer + 263 days. IVF Day-5 → transfer + 261 days.
How This Calculator Works
This calculator uses Nägele's rule to estimate due dates — adding 280 days to the first day of your last period. For IVF pregnancies, we adjust based on the embryo transfer date and the embryo's age (Day 3 or Day 5).
Results are approximate and may differ slightly based on your individual cycle length or medical factors.
LMP Method
Adds 280 days (40 weeks) to the first day of your last menstrual period.
Day-5 Transfer
Adds 261 days to the transfer date (accounts for 5 days of embryo development).
Day-3 Transfer
Adds 263 days to the transfer date (accounts for 3 days of embryo development).
What Your Results Mean
- EDD: The estimated date when the baby is expected to arrive.
- Gestational Age: How far along the pregnancy is, measured in weeks and days.
- Trimesters: The three main phases of pregnancy development.
- Milestones: Important prenatal tests and checkups scheduled throughout pregnancy.
IVF Dating Explained
Why does IVF show 2w5d after a Day-5 transfer?
Gestational age is always counted from the equivalent LMP (last menstrual period) — not from the embryo transfer day.
Day-3 TransferDay-3 Transfer: ≈ 2w 3d gestational age
Day-5 TransferDay-5 Transfer: ≈ 2w 5d gestational age
This convention aligns IVF pregnancies with natural conceptions, allowing doctors to compare milestones on the same timeline.
For Surrogates
Tracking your due date allows better communication with your agency and medical team. Stay informed about key milestones and appointments throughout your pregnancy.
- Plan ahead for key prenatal tests
- Track trimester transitions
- Coordinate with your coordinator
For Intended Parents
Knowing your estimated due date helps you plan travel, baby preparations, and clinic coordination. Use this information to align your surrogate's timeline with your delivery plans.
- Plan travel arrangements
- Prepare the nursery on time
- Coordinate with your agency
Frequently Asked Questions
1. How accurate is this due date calculator?
2. Can I use this calculator for IVF embryo transfers?
Yes. This tool supports both natural conception and IVF transfers. Simply select "Date of Day-3" or "Date of Day-5 Blastocyst Transfer" and enter your transfer date. The calculator automatically converts your IVF transfer into an equivalent LMP and estimates your due date, current gestational age, and key pregnancy milestones.
3. What if my menstrual cycle isn't 28 days long?
This calculator assumes a 28-day cycle for natural conception. If your cycle is longer or shorter, your ovulation day may differ, shifting the due date by a few days. Your fertility clinic or OB/GYN can provide a more precise date using ultrasound or cycle-tracking data.
4. What do the trimester ranges mean?
Pregnancy is divided into three trimesters: First Trimester (Week 0 – 13+6 days), Second Trimester (Week 14 – 27+6 days), and Third Trimester (Week 28 – 40+0 days). The calculator automatically shows the exact calendar dates for each trimester based on your entered information.
5. What are the key milestones shown in my results?
You'll see important prenatal checkpoints including: 10–12 weeks (NIPT or NT screening), 15–20 weeks (Amniocentesis window), 18–22 weeks (Detailed anatomy scan), 24–28 weeks (Glucose tolerance test), 36–37 weeks (Group B Strep test and weekly visits), and 40 weeks (Estimated due date).
6. Why is my gestational age different from fetal age?
Gestational age counts from the first day of your last menstrual period—about two weeks before conception actually occurs. Fetal age measures from the actual conception date. This is why gestational age is typically about two weeks longer than fetal age.
7. When should I contact my doctor about my due date?
If your ultrasound measurements differ from your calculator result by more than 7 days in the first trimester, or if you're experiencing irregular cycles or IVF complications, it's best to confirm your estimated due date with your provider. This calculator is for educational use only and not a substitute for medical advice.
8. Why does the calculator show 2 weeks and 5 days pregnant after a Day-5 blastocyst transfer?
That's because gestational age is always counted from the equivalent "LMP" (last menstrual period)—not the embryo transfer date itself. In IVF, a Day-5 blastocyst transfer corresponds to approximately 2 weeks and 5 days of gestation, while a Day-3 transfer corresponds to 2 weeks and 3 days. This convention aligns IVF pregnancies with natural conceptions, allowing doctors to compare ultrasound and growth milestones on the same gestational timeline.
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Ready to Begin Your Surrogacy Journey?
Whether you're looking to become a surrogate or start your family through surrogacy, we're here to guide you every step of the way.
This calculator provides educational estimates only and should not be considered medical advice. Results may vary based on individual circumstances. Always consult with your healthcare provider for personalized medical guidance.