Pregnancy is a remarkable journey, typically lasting around 40 weeks (or 9 months) from the first day of the Last Menstrual Period (LMP). This calculator helps you track your progress based on your Estimated Due Date (EDD) and the current date. It's important to remember that the 40-week count is a guideline; babies arrive at their own time, and variations are normal.
How the Calculation Works
This calculator determines the number of weeks and days that have passed since conception (or more practically, since the LMP, which is the standard clinical starting point). It then translates this duration into completed months and current weeks.
Weeks Calculation: The difference in days between the EDD and "Today's Date" is calculated. This is then divided by 7 to get the total number of weeks and remaining days until the due date.
Progress Calculation: By subtracting the remaining weeks from the total pregnancy duration (40 weeks), we find the number of weeks and days that have already passed.
Month Conversion: Pregnancy months are often calculated differently than calendar months. A common method is to consider each month to be approximately 4.33 weeks (30.33 days). This calculator uses a more direct approach by calculating weeks and days, and then presenting the closest equivalent in months and weeks for clarity. A typical conversion is:
1-12 weeks: First Month (approx.)
13-16 weeks: Second Month (approx.)
17-20 weeks: Third Month (approx.)
21-24 weeks: Fourth Month (approx.)
25-28 weeks: Fifth Month (approx.)
29-32 weeks: Sixth Month (approx.)
33-36 weeks: Seventh Month (approx.)
37-40 weeks: Eighth Month (approx.)
40+ weeks: Ninth Month (approx.)
This calculator provides a more precise breakdown in completed weeks and days, which can then be loosely associated with these monthly milestones.
Understanding Trimesters
Pregnancy is divided into three trimesters, each with distinct developmental stages for the baby and changes for the mother:
First Trimester (Weeks 1-12): This is a critical period of organ development. Many early pregnancy symptoms, like fatigue and nausea, are common.
Second Trimester (Weeks 13-27): Often considered the "golden period" of pregnancy, as many early symptoms subside. The baby grows rapidly, and movements may be felt.
Third Trimester (Weeks 28-40+): The final stretch where the baby gains weight and prepares for birth. Endurance may decrease, and discomforts might increase.
Disclaimer
This calculator is for informational purposes only and should not replace professional medical advice. Always consult with your healthcare provider for accurate dating, personalized guidance, and any concerns regarding your pregnancy. Your EDD is an estimate, and actual delivery dates can vary.
function calculatePregnancyMonths() {
var dueDateInput = document.getElementById("dueDate");
var currentDateInput = document.getElementById("currentDate");
var resultDiv = document.getElementById("result");
var eddStr = dueDateInput.value;
var currentDateStr = currentDateInput.value;
if (!eddStr || !currentDateStr) {
resultDiv.innerHTML = "Please enter both dates.";
return;
}
var edd = new Date(eddStr);
var currentDate = new Date(currentDateStr);
// Ensure dates are valid
if (isNaN(edd.getTime()) || isNaN(currentDate.getTime())) {
resultDiv.innerHTML = "Invalid date format.";
return;
}
// Check if current date is after due date
if (currentDate > edd) {
resultDiv.innerHTML = "Today's date cannot be after the Estimated Due Date.";
return;
}
// Calculate the difference in milliseconds
var timeDiff = edd.getTime() – currentDate.getTime();
// Convert milliseconds to days
var daysRemaining = Math.ceil(timeDiff / (1000 * 3600 * 24));
// Total pregnancy duration is typically 40 weeks = 280 days
var totalPregnancyDays = 280;
// Calculate days passed
var daysPassed = totalPregnancyDays – daysRemaining;
// Ensure daysPassed is not negative (e.g., if current date is very early)
if (daysPassed < 0) {
daysPassed = 0; // If today is before the EDD calculation starts, assume 0 days passed.
}
// Calculate weeks and days passed
var weeksPassed = Math.floor(daysPassed / 7);
var remainingDays = daysPassed % 7;
// Calculate full months passed (approximate, based on 4.33 weeks/month)
// Or more directly, based on week ranges for clarity
var completedMonths = Math.floor(weeksPassed / 4); // Simple approximation, often a bit off
// A better way to present progress is by weeks
var displayMonths = "";
if (weeksPassed < 13) {
displayMonths = "First Month";
} else if (weeksPassed < 17) {
displayMonths = "Second Month";
} else if (weeksPassed < 21) {
displayMonths = "Third Month";
} else if (weeksPassed < 25) {
displayMonths = "Fourth Month";
} else if (weeksPassed < 29) {
displayMonths = "Fifth Month";
} else if (weeksPassed < 33) {
displayMonths = "Sixth Month";
} else if (weeksPassed < 37) {
displayMonths = "Seventh Month";
} else if (weeksPassed < 41) {
displayMonths = "Eighth Month";
} else {
displayMonths = "Ninth Month (or beyond)";
}
resultDiv.innerHTML =
"You are approximately " + weeksPassed + " weeks and " + remainingDays + " days pregnant. " +
"This is around the " + displayMonths + " mark.";
}