ivf pregnancy week by week calculator

How this IVF due date calculator works

Pregnancy dating after IVF is more precise than natural conception dating because your clinic knows exactly when the embryo transfer happened and how old the embryo was at transfer.

Instead of guessing ovulation, we calculate from known dates:

• Conception-equivalent date = transfer date minus embryo age (in days)
• Estimated due date (EDD) = conception-equivalent date + 266 days
• LMP-equivalent date = conception-equivalent date - 14 days

From that LMP-equivalent date, we can estimate your current pregnancy week and day just like a standard obstetric chart.

Why IVF dating is different (and often more accurate)

In spontaneous conception, due date estimates are usually based on the first day of your last menstrual period and then adjusted with ultrasound. With IVF, clinicians already know the embryo development stage and transfer timing, which improves dating accuracy from day one.

Typical examples

• Day 5 transfer: gestational age is typically 2 weeks + 5 days on transfer day.
• Day 3 transfer: gestational age is typically 2 weeks + 3 days on transfer day.
• Day 6 transfer: gestational age is typically 2 weeks + 6 days on transfer day.

How to use the calculator

1. Enter your embryo transfer date.
2. Select whether your embryo was Day 3, Day 5, or Day 6.
3. Choose an “as of” date (today is auto-filled).
4. Click Calculate IVF Timeline.

You’ll get:

• Estimated due date
• Current gestational age
• LMP-equivalent date
• Days remaining until due date
• A full week-by-week timeline (Weeks 1–40)

IVF pregnancy week-by-week overview

First trimester (Weeks 1–13)

This period includes implantation, rising hCG, early ultrasounds, and organ formation. Many clinics schedule frequent support and monitoring in these weeks, especially after fertility treatment.

• Weeks 4–5: beta hCG and early placement checks
• Weeks 5–7: gestational sac, yolk sac, and heartbeat visibility
• Weeks 10–13: transition from fertility clinic to OB care (varies by clinic)

Second trimester (Weeks 14–27)

This is often the most physically comfortable trimester for many people. Growth accelerates, and anatomy assessments become central.

• Weeks 18–22: detailed anatomy scan
• Week 24 onward: viability milestones and continued growth surveillance
• Weeks 24–28: glucose screening is commonly scheduled

Third trimester (Weeks 28–40)

Focus shifts to fetal position, growth trends, maternal blood pressure monitoring, and delivery planning. IVF pregnancies may include additional surveillance depending on history and clinic protocol.

• Weeks 32–36: growth checks and birth planning
• Week 37: early term
• Weeks 39–40: full term window and due date period

Frequently asked questions

Does frozen embryo transfer (FET) change the due date formula?

No. Fresh and frozen cycles use the same embryo-age logic for dating. The transfer date and embryo day determine the core calculation.

Can my due date change after ultrasound?

Possibly. Even in IVF, your care team may make small adjustments based on early ultrasound findings and clinical judgment.

Is this calculator valid for twins?

The dating method is still valid. However, monitoring, growth expectations, and delivery timing differ in multiple gestations, so always rely on your specialist team.

What if my clinic gives a different date?

Always use your clinic’s official date. This tool is educational and planning-focused, not a replacement for medical care.