Gestational Age Calculator in Weeks

Gestational Age Calculator

function calculateGestationalAge() { var lmpDateInput = document.getElementById("lmpDate").value; var currentDateInput = document.getElementById("currentDate").value; var resultDiv = document.getElementById("gestationalAgeResult"); if (!lmpDateInput || !currentDateInput) { resultDiv.innerHTML = "Please enter both LMP Date and Current Date."; return; } var lmpDate = new Date(lmpDateInput); var currentDate = new Date(currentDateInput); // Set time to midnight to avoid issues with timezones/daylight saving affecting day count lmpDate.setHours(0, 0, 0, 0); currentDate.setHours(0, 0, 0, 0); if (isNaN(lmpDate.getTime()) || isNaN(currentDate.getTime())) { resultDiv.innerHTML = "Invalid date format. Please use YYYY-MM-DD."; return; } if (lmpDate.getTime() > currentDate.getTime()) { resultDiv.innerHTML = "LMP Date cannot be after the Current Date."; return; } var timeDiff = Math.abs(currentDate.getTime() – lmpDate.getTime()); var diffDays = Math.ceil(timeDiff / (1000 * 60 * 60 * 24)); var weeks = Math.floor(diffDays / 7); var days = diffDays % 7; resultDiv.innerHTML = "Your estimated gestational age is: " + weeks + " weeks and " + days + " days."; } // Set current date input to today's date by default window.onload = function() { var today = new Date(); var dd = String(today.getDate()).padStart(2, '0'); var mm = String(today.getMonth() + 1).padStart(2, '0'); //January is 0! var yyyy = today.getFullYear(); document.getElementById("currentDate").value = yyyy + '-' + mm + '-' + dd; };

Understanding Gestational Age

Gestational age is a crucial measurement used during pregnancy to determine how far along a pregnancy is. It's typically calculated from the first day of the woman's last menstrual period (LMP) to the current date. This method assumes a regular 28-day menstrual cycle with ovulation occurring on day 14.

Why is Gestational Age Important?

Knowing the gestational age is vital for several reasons:

• Monitoring Fetal Development: It helps healthcare providers track the baby's growth and development against expected milestones for that stage of pregnancy.
• Scheduling Tests and Screenings: Many prenatal tests, such as genetic screenings and ultrasounds, are time-sensitive and must be performed within specific gestational age windows.
• Estimating Due Date: While not an exact science, gestational age is the primary factor in calculating an estimated due date (EDD), which is typically 40 weeks from the LMP.
• Identifying Complications: Deviations from expected growth patterns for a given gestational age can signal potential complications or the need for further investigation.
• Planning Delivery: It helps in making informed decisions about the timing and method of delivery, especially in cases of preterm labor or post-term pregnancy.

How is Gestational Age Calculated?

The most common methods for calculating gestational age include:

1. Last Menstrual Period (LMP): This is the method used in this calculator. It counts the number of weeks and days from the first day of your last menstrual period.
2. Early Ultrasound: An ultrasound performed in the first trimester (typically between 6 and 12 weeks) can provide a very accurate gestational age by measuring the crown-rump length (CRL) of the embryo/fetus. This method is often used to confirm or adjust the gestational age derived from the LMP, especially if the LMP is uncertain or irregular.
3. Assisted Reproductive Technology (ART): For pregnancies conceived via IVF or other ART methods, gestational age can be precisely calculated based on the date of egg retrieval or embryo transfer.

Using the Calculator

To use this Gestational Age Calculator:

1. Enter your Last Menstrual Period (LMP) Date: Select the first day of your last period.
2. Enter the Current Date: This field will typically pre-fill with today's date, but you can adjust it if you want to calculate gestational age for a past or future date.
3. Click "Calculate Gestational Age": The calculator will then display your estimated gestational age in weeks and days.

Disclaimer: This calculator provides an estimate of gestational age based on the information you provide. It is not a substitute for professional medical advice. Always consult with your healthcare provider for accurate dating of your pregnancy and for any medical concerns.