Day 3 Embryo (Cleavage Stage)
Day 5 Embryo (Blastocyst Stage)
Your estimated due date and gestational age will appear here.
Understanding IVF Gestation Calculation
Calculating gestational age in the context of In Vitro Fertilization (IVF) requires understanding specific timelines related to embryo development and transfer. Unlike natural conception where the start of the last menstrual period (LMP) is the primary reference, IVF gestation is calculated from the date of embryo transfer. This method provides a more precise starting point for tracking pregnancy progression.
The calculation depends on the stage of the embryo at the time of transfer. Typically, embryos are transferred either as Day 3 (cleavage stage) or Day 5 (blastocyst stage) embryos. Each stage corresponds to a different number of days post-fertilization.
Day 3 Embryo: Fertilization is considered to have occurred approximately 3 days prior to the transfer date.
Day 5 Embryo: Fertilization is considered to have occurred approximately 5 days prior to the transfer date.
To determine the estimated due date (EDD) and gestational age, we add the appropriate number of days to the transfer date to establish a "fertilization date" equivalent, and then count forward from there. A full-term pregnancy is typically considered 40 weeks (280 days) from the first day of the LMP in traditional dating, or approximately 38 weeks (266 days) from the estimated date of fertilization.
How the Calculator Works:
This calculator uses the following logic:
Determine Fertilization Date Equivalent:
If a Day 3 embryo was transferred, the calculator assumes fertilization occurred 3 days before the transfer date.
If a Day 5 embryo was transferred, the calculator assumes fertilization occurred 5 days before the transfer date.
Calculate Gestational Age: The current date is compared to the calculated fertilization date equivalent to determine the current gestational age in weeks and days.
Calculate Estimated Due Date (EDD): The estimated due date is calculated by adding 38 weeks (266 days) to the fertilization date equivalent.
Why is this important?
Accurate gestational dating is crucial for several reasons in IVF pregnancies:
Monitoring Fetal Development: Allows healthcare providers to compare the fetus's growth and development against standard milestones.
Scheduling Appointments and Tests: Essential for timing prenatal check-ups, ultrasounds, and screening tests appropriately.
Managing Potential Complications: Helps identify pregnancies that may be at risk for preterm labor or post-term delivery.
While this calculator provides an estimate, always confirm your gestational age and due date with your healthcare provider, as they will use various clinical factors and ultrasounds for the most accurate assessment.
function calculateGestation() {
var transferDateInput = document.getElementById("transferDate");
var embryoStageSelect = document.getElementById("embryoStage");
var resultDiv = document.getElementById("result");
var transferDateValue = transferDateInput.value;
var embryoStage = parseInt(embryoStageSelect.value);
if (!transferDateValue) {
resultDiv.innerHTML = "Please select an embryo transfer date.";
return;
}
var transferDate = new Date(transferDateValue);
var today = new Date();
today.setHours(0, 0, 0, 0); // Normalize today's date to midnight
// Adjust transfer date to midnight for accurate calculation
transferDate.setHours(0, 0, 0, 0);
var fertilizationDaysToAdd = embryoStage;
var fertilizationDate = new Date(transferDate.getTime());
fertilizationDate.setDate(transferDate.getDate() – fertilizationDaysToAdd);
// Calculate Gestational Age
var timeDifference = today.getTime() – fertilizationDate.getTime();
var daysDifference = Math.floor(timeDifference / (1000 * 60 * 60 * 24));
var gestationalWeeks = Math.floor(daysDifference / 7);
var gestationalDays = daysDifference % 7;
// Calculate Estimated Due Date (38 weeks from fertilization date)
var eddDate = new Date(fertilizationDate.getTime());
eddDate.setDate(fertilizationDate.getDate() + 266); // 266 days = 38 weeks
// Function to format date as MM/DD/YYYY
function formatDate(date) {
var month = (date.getMonth() + 1).toString().padStart(2, '0');
var day = date.getDate().toString().padStart(2, '0');
var year = date.getFullYear();
return month + '/' + day + '/' + year;
}
var formattedEdd = formatDate(eddDate);
resultDiv.innerHTML =
"Estimated Gestational Age: " +
gestationalWeeks + " weeks and " + gestationalDays + " days" +
"Estimated Due Date: " + formattedEdd + "";
}