Accurately determining the Estimated Date of Delivery (EDD) and Estimated Gestational Age (EGA) for pregnancies conceived via In Vitro Fertilization.
Bypassing the standard Last Menstrual Period (LMP) method entirely due to ovulation induction suppression.
Interpreting Anti-Müllerian Hormone (AMH) levels for ovarian reserve testing.
The Dating Mandate
In an IVF pregnancy, the exact date of fertilization is a known scientific fact. Under no circumstances should early ultrasound/crown-rump length or LMP override the calculated IVF date. The IVF date is neurologically absolute.
Section 2
Formula & Logic
Formula Rules
Standard Human Gestational Period = 280 days (from LMP) or 266 days (from conception).
For a Day 3 Embryo (Cleavage Stage): EDD = Transfer Date + 266 Days - 3 Days
For a Day 5 Embryo (Blastocyst): EDD = Transfer Date + 266 Days - 5 Days
AMH Interpretation
> 3.3 ng/mL
High / PCOM morphology (risk of Ovarian Hyperstimulation Syndrome)
Very low reserve (poor responder to egg retrieval)
Section 3
Pearls/Pitfalls
Key Misconceptions
A very low AMH (<0.7) means the patient will have immense difficulty retrieving multiple eggs during IVF. It DOES NOT mean the patient cannot spontaneously get pregnant globally; egg quality is tied to age, not AMH pool size.
Oral contraceptive pills (OCPs) can artificially suppress AMH levels. If a patient gets an AMH tested while on the pill, the result is falsely terrifying.
Section 4
Next Steps
Obstetric Management of IVF Pregnancies
01
Continue progesterone supplementation through 10-12 weeks until the placenta takes over production (corpus luteum rescue).
02
Schedule a viability ultrasound at 7-8 weeks.
03
Offer fetal echocardiogram at 20-22 weeks due to the slightly increased background risk of congenital heart defects in IVF/ICSI neonates.
04
Monitor for preeclampsia (IVF with frozen embryo transfer strongly correlates with higher risk of hypertensive disorders of pregnancy).
Section 5
Evidence Appraisal
ACOG Guidelines
Methods for Estimating the Due Date.
ACOG Committee Opinion No. 700. • Obstet Gynecol.. 2017;Explicitly mandates that pregnancies conceived with Assisted Reproductive Technology must be dated exclusively by the embryonic age and transfer date, disregarding LMP and early ultrasound.
Section 6
Literature
Historical Context
The absolute precision of IVF dating revolutionized modern obstetrics, allowing clinicians to bypass the inherent unreliability of maternal menstrual history and identifying cases of true fetal growth restriction (FGR) with perfect denominators.
