Compute Estimated Gestational Age from Due Date (Javascript)

computeEGA

// Usage: computeEGA(2014, 4, 14);
// Computes the Estimated Gestational Age of a patient based on today's date and her Expected Due Date (EDD)

// Sample data
var iDueDateYear = 2014;
var iDueDateMonth = 4;
var iDueDateDay = 14;

function computeEGA( iDueDateYear, iDueDateMonth, iDueDateDay ) {
	var dToday   = new Date();
	var dDueDate = new Date( iDueDateYear, iDueDateMonth-1, iDueDateDay );
	var iDaysUntilDueDate = (dDueDate - dToday) / (1000 * 60 * 60 * 24 );
	var iTotalDaysInPregnancy = 40*7;
	var iGestationalAgeInDays = iTotalDaysInPregnancy - iDaysUntilDueDate;
	var fGestationalAgeInWeeks = iGestationalAgeInDays / 7;
	var iEGAWeeks = Math.floor( fGestationalAgeInWeeks );
	var iEGADays = ((fGestationalAgeInWeeks % 1)*7).toFixed(0)

	console.log( iEGAWeeks + " weeks" );
	console.log( iEGADays + " days" );
}