Enter your pre-pregnancy details to estimate your recommended total and weekly weight gain during pregnancy.
Enter your weight in kilograms (kg).
— Select Category —
Underweight (BMI < 18.5)
Normal Weight (18.5 <= BMI < 25)
Overweight (25 <= BMI < 30)
Obese (BMI >= 30)
Your BMI category before pregnancy.
Enter the current week of pregnancy (1-40).
Your Pregnancy Weight Gain Information
Recommended Total Gain:
—
First Trimester Gain (approx): — kg
Second Trimester Gain (approx): — kg
Third Trimester Gain (approx): — kg
Target Weekly Gain (after Week 20): — kg/week
Formula Basis: Recommendations are based on IOM (Institute of Medicine) guidelines, which vary by pre-pregnancy BMI. Total gain is distributed across trimesters, with more significant gain typically in the second and third trimesters.
Recommended vs. Your Estimated Weight Gain Progression
Recommended Pregnancy Weight Gain Ranges by BMI Category
BMI Category
Recommended Total Gain (kg)
Recommended Weekly Gain (after Week 13) (kg/week)
Underweight (BMI < 18.5)
12.5 – 18.0
0.5 – 0.6
Normal Weight (18.5 <= BMI < 25)
11.5 – 16.0
0.4 – 0.5
Overweight (25 <= BMI < 30)
7.0 – 11.5
0.3 – 0.4
Obese (BMI >= 30)
5.0 – 9.0
0.2 – 0.3
What is Ideal Weight Gain During Pregnancy?
Ideal weight gain during pregnancy refers to the amount of weight a pregnant person is recommended to gain throughout their gestation period. This gain is crucial for both maternal health and fetal development. It supports the growth of the fetus, placenta, amniotic fluid, maternal tissues (like the uterus and breasts), and increased maternal blood volume. The recommended amount is not a one-size-fits-all figure; it is highly individualized and primarily determined by the pregnant person's pre-pregnancy Body Mass Index (BMI) category. Healthcare providers use these guidelines to monitor a healthy pregnancy and identify potential risks associated with insufficient or excessive weight gain. For instance, gaining too little weight can be linked to low birth weight, premature birth, and developmental issues, while gaining too much can increase the risk of complications like gestational diabetes, preeclampsia, and having a larger-than-average baby (macrosomia), which can lead to complications during delivery.
Who Should Use This Calculator?
This calculator is designed for individuals who are pregnant or planning a pregnancy. Anyone seeking to understand the recommended weight gain based on their specific pre-pregnancy health indicators and current stage of pregnancy will find this tool beneficial. This includes:
Pregnant individuals wanting to track their progress.
Expectant parents seeking to understand general guidelines.
Individuals looking for a personalized estimate of ideal weight gain targets.
Those who wish to have a clearer idea of what constitutes healthy weight gain for their unique situation, to discuss with their healthcare provider.
Common Misconceptions
Several myths surround pregnancy weight gain. One common misconception is that pregnant individuals should "eat for two," implying unlimited calorie intake. In reality, while nutritional needs increase, the increase is modest, especially in the first trimester. Another myth is that weight gain is solely about the baby's weight; however, the gain includes the baby, placenta, amniotic fluid, increased blood volume, breast tissue, uterine growth, and maternal fat stores. Some also believe that all weight gained during pregnancy is permanent, which isn't necessarily true; with healthy lifestyle habits post-birth, much of the weight can be lost.
Pregnancy Weight Gain Formula and Mathematical Explanation
The calculation of ideal pregnancy weight gain is primarily based on established guidelines from bodies like the Institute of Medicine (IOM) or the National Academy of Medicine. These guidelines categorize recommended total weight gain and weekly gain based on pre-pregnancy BMI. While there isn't a single, complex mathematical formula to *derive* these ranges from scratch, the calculator applies these ranges based on user inputs. Here's how the logic works:
1. Determine Pre-Pregnancy BMI Category:
The calculator takes the user's pre-pregnancy BMI category (underweight, normal, overweight, obese) as a primary input. This categorization dictates the target weight gain.
2. Establish Recommended Total Weight Gain:
Based on the BMI category, a specific range for total recommended weight gain is applied:
Underweight (BMI < 18.5): 12.5 – 18.0 kg
Normal Weight (18.5 <= BMI < 25): 11.5 – 16.0 kg
Overweight (25 <= BMI < 30): 7.0 – 11.5 kg
Obese (BMI >= 30): 5.0 – 9.0 kg
The calculator typically targets the midpoint or a specific value within this range for simplicity or provides the range itself. For this calculator's primary output, we'll aim for the midpoint of the recommended total gain for illustrative purposes.
3. Estimate Trimester-Specific Gains:
Weight gain is not linear throughout pregnancy. Guidelines suggest:
First Trimester (Weeks 1-13): Approximately 1-2 kg total gain, regardless of BMI category.
Second Trimester (Weeks 14-27): Approximately 4-6 kg gain.
Third Trimester (Weeks 28-40): Approximately 4-6 kg gain.
The calculator approximates these values. The gain in the first trimester is relatively small. The second and third trimesters see more significant and consistent gain.
4. Calculate Target Weekly Gain:
After the first trimester, the recommended weekly gain becomes more consistent and is linked to the BMI category:
Underweight: ~0.5 – 0.6 kg/week
Normal Weight: ~0.4 – 0.5 kg/week
Overweight: ~0.3 – 0.4 kg/week
Obese: ~0.2 – 0.3 kg/week
The calculator will use the upper end of the range for the "target weekly gain" after week 20 for a more ambitious but still healthy target.
Variable Explanations
Variable
Meaning
Unit
Typical Range
Pre-Pregnancy Weight
Weight before conception.
kg
40 – 150+
Pre-Pregnancy BMI Category
Classification based on height and weight pre-pregnancy.
Category
Underweight, Normal, Overweight, Obese
Gestational Age
Current stage of pregnancy.
Weeks
1 – 40
Recommended Total Gain
Target total weight gain for the entire pregnancy.
kg
5.0 – 18.0
First Trimester Gain (Est.)
Estimated weight gain in the first 13 weeks.
kg
1.0 – 2.0
Second Trimester Gain (Est.)
Estimated weight gain from week 14 to 27.
kg
4.0 – 6.0
Third Trimester Gain (Est.)
Estimated weight gain from week 28 to 40.
kg
4.0 – 6.0
Target Weekly Gain (Post-Week 20)
Recommended average weekly gain after the first 20 weeks.
kg/week
0.2 – 0.6
Practical Examples (Real-World Use Cases)
Example 1: Sarah (Normal Weight)
Scenario: Sarah is 28 years old and had a healthy lifestyle before getting pregnant. Her pre-pregnancy weight was 62 kg, and she had a BMI within the normal range (18.5-24.9). She is currently 15 weeks pregnant.
Inputs:
Pre-Pregnancy Weight: 62 kg
Pre-Pregnancy BMI Category: Normal Weight
Current Gestational Age: 15 weeks
Calculator Output (Estimated):
Recommended Total Gain: ~13.75 kg (midpoint of 11.5-16.0 kg)
First Trimester Gain (approx): 1.5 kg
Second Trimester Gain (approx): 5.0 kg
Third Trimester Gain (approx): 5.0 kg
Target Weekly Gain (after Week 20): ~0.45 kg/week
Interpretation: Sarah falls into the normal weight category, so she has a generous recommended weight gain range. The calculator suggests a total gain of around 13.75 kg. Since she is already 15 weeks pregnant, she has likely gained some weight in the first trimester. Her focus should now be on achieving steady gain through the second and third trimesters, aiming for approximately 0.45 kg per week until the end of her pregnancy. She should ensure nutrient-dense foods to support fetal growth without excessive calorie intake.
Example 2: Mark (Obese)
Scenario: Maria is 35 years old and has struggled with weight management. Her pre-pregnancy weight was 95 kg, placing her in the obese BMI category (>=30). She is currently 25 weeks pregnant.
Inputs:
Pre-Pregnancy Weight: 95 kg
Pre-Pregnancy BMI Category: Obese
Current Gestational Age: 25 weeks
Calculator Output (Estimated):
Recommended Total Gain: ~7.0 kg (midpoint of 5.0-9.0 kg)
First Trimester Gain (approx): 1.5 kg
Second Trimester Gain (approx): 4.0 kg
Third Trimester Gain (approx): 4.0 kg
Target Weekly Gain (after Week 20): ~0.25 kg/week
Interpretation: Maria is in the obese category, for whom the recommended total weight gain is significantly lower than for normal-weight individuals. The calculator suggests a total gain of around 7.0 kg. At 25 weeks, she has already completed the first and second trimesters and is well into the third. The estimated gains for the first two trimesters are shown, and her current focus should be on mindful eating to achieve a gain of approximately 0.25 kg per week for the remainder of her pregnancy. This is essential to minimize risks associated with excessive weight gain in pregnancy, such as gestational diabetes and complications during delivery.
How to Use This Pregnancy Weight Gain Calculator
Input Pre-Pregnancy Weight: Enter your weight in kilograms (kg) as it was before you became pregnant.
Select BMI Category: Choose the category that best describes your Body Mass Index (BMI) before pregnancy. If you're unsure of your exact BMI, select the category that aligns with your general weight status (underweight, normal, overweight, or obese).
Enter Gestational Age: Input the current number of weeks you are into your pregnancy.
Click 'Calculate': The calculator will process your inputs and display:
Recommended Total Gain: The target total weight you should aim to gain by the end of your pregnancy.
Trimester Gains: Approximate weight gain targets for each trimester.
Target Weekly Gain: The recommended average weekly weight gain, particularly relevant after the first 20 weeks.
Interpret Results: Compare the results with your current weight gain. Remember these are guidelines, and individual needs can vary.
Use 'Reset': Click 'Reset' to clear all fields and start over with new inputs.
Copy Results: Click 'Copy Results' to copy the calculated information, which can be useful for sharing with your healthcare provider or keeping personal records.
Decision-Making Guidance: Use these results as a starting point for conversations with your doctor or midwife. They can provide the most accurate advice tailored to your specific health status, medical history, and pregnancy progression. If your current weight gain is significantly above or below the recommended range, discuss this with your healthcare provider to understand potential implications and strategies.
Key Factors That Affect Pregnancy Weight Gain
Several factors influence how much weight is gained during pregnancy, extending beyond the basic BMI categories:
Pre-Pregnancy BMI: As highlighted, this is the primary determinant. Lower pre-pregnancy BMIs require greater gain, while higher BMIs necessitate more modest gain to mitigate risks.
Maternal Age: While not a direct guideline factor, older mothers may sometimes face different metabolic responses or pre-existing conditions that affect weight gain.
Multiple Gestations (Twins, Triplets, etc.): Carrying more than one baby naturally requires a higher total weight gain to support the growth of all fetuses and placentas.
Dietary Habits and Nutrition: The quality and quantity of food intake are paramount. A balanced diet rich in essential nutrients supports healthy fetal development and appropriate maternal weight gain. Excessive intake of calorie-dense, nutrient-poor foods contributes to excessive gain.
Physical Activity Levels: Regular, moderate exercise is encouraged during pregnancy. It helps manage weight gain, improves maternal fitness, and can reduce the risk of certain complications. However, extreme exercise regimens might be detrimental.
Underlying Medical Conditions: Conditions such as gestational diabetes, thyroid issues, or eating disorders can significantly impact weight gain patterns and require careful medical management.
Cravings and Aversions: Hormonal changes can lead to intense food cravings or strong aversions, potentially influencing dietary choices and, consequently, weight gain.
Socioeconomic Factors: Access to nutritious food, healthcare, and safe environments for physical activity can indirectly influence weight management during pregnancy.
Frequently Asked Questions (FAQ)
How much weight should I gain in the first trimester?
Typically, about 1 to 2 kg (2 to 4 lbs) is recommended for most women in the first trimester, regardless of their pre-pregnancy BMI. Some women may even lose weight initially due to nausea and vomiting.
Is it okay if I gain weight faster than recommended?
Gaining weight significantly faster than recommended can increase risks like gestational diabetes, preeclampsia, and delivering a large baby. It's important to discuss rapid weight gain with your healthcare provider.
What if I'm not gaining enough weight?
Insufficient weight gain can be associated with risks like low birth weight and preterm labor. Your doctor may recommend dietary changes or nutritional supplements.
Does my pre-pregnancy weight matter more than my current weight?
Yes, your pre-pregnancy BMI is the primary factor used to determine recommended weight gain ranges. Your current weight and rate of gain are monitored throughout pregnancy.
How is BMI calculated?
BMI is calculated using the formula: weight (kg) / [height (m)]^2. For example, if you weigh 65 kg and are 1.65 meters tall, your BMI is 65 / (1.65 * 1.65) ≈ 23.8.
What counts towards pregnancy weight gain?
Weight gain includes the baby, placenta, amniotic fluid, increased blood volume, larger uterus, breast tissue development, and maternal fat stores for energy.
Should I diet during pregnancy?
Crash dieting is generally not recommended during pregnancy as it can deprive the fetus of essential nutrients. Focus on a balanced, nutrient-dense diet and healthy eating patterns advised by your healthcare provider.
How much weight do healthcare providers typically recommend losing after birth?
While the focus is on postpartum recovery, many aim to lose about half the pregnancy weight within the first six weeks. Significant weight loss efforts are usually advised after 6-8 weeks postpartum, coupled with healthy eating and exercise.
Learn about risk factors, symptoms, and management of gestational diabetes.
var chartInstance = null; // Global variable to hold the chart instance
function calculateWeightGain() {
// Clear previous errors
clearErrors();
// Get input values
var prePregnancyWeight = parseFloat(document.getElementById("prePregnancyWeight").value);
var prePregnancyBMIValue = document.getElementById("prePregnancyBMI").value;
var gestationalAge = parseInt(document.getElementById("gestationalAge").value);
// — Input Validation —
var errorsFound = false;
if (isNaN(prePregnancyWeight) || prePregnancyWeight <= 0) {
displayError("prePregnancyWeightError", "Please enter a valid pre-pregnancy weight.");
errorsFound = true;
}
if (prePregnancyBMIValue === "") {
displayError("prePregnancyBMIError", "Please select your pre-pregnancy BMI category.");
errorsFound = true;
}
if (isNaN(gestationalAge) || gestationalAge 40) {
displayError("gestationalAgeError", "Please enter a gestational age between 1 and 40 weeks.");
errorsFound = true;
}
if (errorsFound) {
return; // Stop calculation if validation fails
}
// — Define Recommendations based on BMI Category —
var recommendations = {
underweight: { totalGainRange: [12.5, 18.0], weeklyGainRange: [0.5, 0.6] },
normal: { totalGainRange: [11.5, 16.0], weeklyGainRange: [0.4, 0.5] },
overweight: { totalGainRange: [7.0, 11.5], weeklyGainRange: [0.3, 0.4] },
obese: { totalGainRange: [5.0, 9.0], weeklyGainRange: [0.2, 0.3] }
};
var recs = recommendations[prePregnancyBMIValue];
if (!recs) {
// Fallback for unexpected BMI values, though select should prevent this
displayError("prePregnancyBMIError", "Invalid BMI category selected.");
return;
}
// Calculate primary result (midpoint of total gain range)
var recommendedTotalGain = (recs.totalGainRange[0] + recs.totalGainRange[1]) / 2;
var formattedTotalGain = recommendedTotalGain.toFixed(2);
// — Intermediate Calculations —
var firstTrimesterGainEst = 1.5; // Standard estimate
var secondTrimesterGainEst, thirdTrimesterGainEst;
// Distribute remaining gain after first trimester
var remainingGain = recommendedTotalGain – firstTrimesterGainEst;
// Basic distribution for second and third trimesters (can be refined)
// If remainingGain is positive, distribute somewhat evenly. If negative (e.g., very low obese target), adjust.
if (remainingGain > 0) {
secondTrimesterGainEst = remainingGain / 2;
thirdTrimesterGainEst = remainingGain / 2;
} else {
// If total recommended gain is less than first trimester estimate, adjust drastically
secondTrimesterGainEst = Math.max(0, remainingGain * 0.7); // Assign a portion, ensure non-negative
thirdTrimesterGainEst = Math.max(0, remainingGain * 0.3);
if (recommendedTotalGain < 5.0) { // Ensure minimums if total is very low
secondTrimesterGainEst = Math.max(0, recommendedTotalGain * 0.4);
thirdTrimesterGainEst = Math.max(0, recommendedTotalGain * 0.3);
}
}
// Ensure gains don't exceed reasonable bounds, especially if total is low
secondTrimesterGainEst = Math.min(secondTrimesterGainEst, recs.totalGainRange[1] – firstTrimesterGainEst);
thirdTrimesterGainEst = Math.min(thirdTrimesterGainEst, recs.totalGainRange[1] – firstTrimesterGainEst – secondTrimesterGainEst);
// Target weekly gain (midpoint of range, applicable after ~week 20)
var targetWeeklyGain = (recs.weeklyGainRange[0] + recs.weeklyGainRange[1]) / 2;
var formattedWeeklyGain = targetWeeklyGain.toFixed(2);
// — Display Results —
document.getElementById("primaryResult").innerText = formattedTotalGain + " kg";
document.getElementById("firstTrimesterGain").innerText = firstTrimesterGainEst.toFixed(2);
document.getElementById("secondTrimesterGain").innerText = secondTrimesterGainEst.toFixed(2);
document.getElementById("thirdTrimesterGain").innerText = thirdTrimesterGainEst.toFixed(2);
document.getElementById("targetWeeklyGain").innerText = formattedWeeklyGain;
// — Update Chart —
updateChart(gestationalAge, recommendedTotalGain, prePregnancyBMIValue);
}
function clearErrors() {
var errorElements = document.querySelectorAll('.error-message');
for (var i = 0; i < errorElements.length; i++) {
errorElements[i].innerText = '';
}
}
function displayError(elementId, message) {
document.getElementById(elementId).innerText = message;
}
function resetCalculator() {
document.getElementById("prePregnancyWeight").value = "";
document.getElementById("prePregnancyBMI").value = "";
document.getElementById("gestationalAge").value = "";
document.getElementById("primaryResult").innerText = "–";
document.getElementById("firstTrimesterGain").innerText = "–";
document.getElementById("secondTrimesterGain").innerText = "–";
document.getElementById("thirdTrimesterGain").innerText = "–";
document.getElementById("targetWeeklyGain").innerText = "–";
clearErrors();
if (chartInstance) {
chartInstance.destroy(); // Destroy existing chart
chartInstance = null;
}
// Re-initialize the canvas context for a clean slate if needed
var canvas = document.getElementById('weightGainChart');
var ctx = canvas.getContext('2d');
ctx.clearRect(0, 0, canvas.width, canvas.height);
}
function copyResults() {
var primaryResult = document.getElementById("primaryResult").innerText;
var firstTrimester = document.getElementById("firstTrimesterGain").innerText;
var secondTrimester = document.getElementById("secondTrimesterGain").innerText;
var thirdTrimester = document.getElementById("thirdTrimesterGain").innerText;
var weeklyGain = document.getElementById("targetWeeklyGain").innerText;
var bmiCategory = document.getElementById("prePregnancyBMI").options[document.getElementById("prePregnancyBMI").selectedIndex].text;
var gestationalAgeInput = document.getElementById("gestationalAge").value;
var prePregnancyWeightInput = document.getElementById("prePregnancyWeight").value;
if (primaryResult === "–") {
alert("Please calculate results first before copying.");
return;
}
var textToCopy = "— Pregnancy Weight Gain Summary —\n\n";
textToCopy += "Pre-Pregnancy Weight: " + prePregnancyWeightInput + " kg\n";
textToCopy += "BMI Category: " + bmiCategory + "\n";
textToCopy += "Current Gestational Age: " + gestationalAgeInput + " weeks\n\n";
textToCopy += "Recommended Total Gain: " + primaryResult + "\n";
textToCopy += "Estimated First Trimester Gain: " + firstTrimester + " kg\n";
textToCopy += "Estimated Second Trimester Gain: " + secondTrimester + " kg\n";
textToCopy += "Estimated Third Trimester Gain: " + thirdTrimester + " kg\n";
textToCopy += "Target Weekly Gain (after Week 20): " + weeklyGain + " kg/week\n\n";
textToCopy += "Note: These are general guidelines based on pre-pregnancy BMI and gestational age. Consult your healthcare provider for personalized advice.";
navigator.clipboard.writeText(textToCopy).then(function() {
alert("Results copied to clipboard!");
}, function(err) {
console.error('Could not copy text: ', err);
prompt("Copy manually:", textToCopy); // Fallback for browsers that don't support clipboard API well
});
}
// — Charting Logic —
function updateChart(currentGestationalAge, recommendedTotalGain, bmiCategory) {
var canvas = document.getElementById('weightGainChart');
var ctx = canvas.getContext('2d');
// Destroy previous chart instance if it exists
if (chartInstance) {
chartInstance.destroy();
}
// Chart data generation
var labels = [];
var recommendedGainData = [];
var estimatedGainData = [];
var firstTrimesterGainEst = 1.5;
var secondTrimesterGainEst = parseFloat(document.getElementById("secondTrimesterGain").innerText);
var thirdTrimesterGainEst = parseFloat(document.getElementById("thirdTrimesterGain").innerText);
var targetWeeklyGain = parseFloat(document.getElementById("targetWeeklyGain").innerText);
// Default gain values if intermediate results are not yet calculated
if (isNaN(secondTrimesterGainEst)) secondTrimesterGainEst = 4.0;
if (isNaN(thirdTrimesterGainEst)) thirdTrimesterGainEst = 4.0;
if (isNaN(targetWeeklyGain)) targetWeeklyGain = 0.4; // Default for chart
// Determine the end week for the chart – usually 40, but adjust if input is less
var chartEndDate = Math.max(currentGestationalAge, 40);
var currentGain = 0;
for (var week = 0; week <= chartEndDate; week++) {
labels.push(week);
// Calculate recommended gain progression
var recGain = 0;
if (week <= 13) {
recGain = firstTrimesterGainEst * (week / 13);
} else if (week <= 27) {
recGain = firstTrimesterGainEst + secondTrimesterGainEst * ((week – 13) / 14);
} else {
recGain = firstTrimesterGainEst + secondTrimesterGainEst + thirdTrimesterGainEst * ((week – 27) / 13);
}
// Cap recommended gain at the calculated total recommended gain
recGain = Math.min(recGain, recommendedTotalGain);
recommendedGainData.push(recGain.toFixed(2));
// Estimate user's current gain based on input gestational age and target weekly gain
var estGain = 0;
if (week <= 13) {
estGain = firstTrimesterGainEst * (Math.min(week, 13) / 13);
} else {
// Rough estimation: use first trimester gain + average gain for subsequent weeks
// This is a simplified model. A more complex one could track based on actual user input vs target.
// For simplicity, we'll show a line that trends towards the total recommended gain based on weekly targets.
estGain = firstTrimesterGainEst + targetWeeklyGain * Math.max(0, week – 13); // Crude linear progression
// Ensure it doesn't exceed the total recommended gain
estGain = Math.min(estGain, recommendedTotalGain);
}
// Cap estimated gain at the total recommended gain
estimatedGainData.push(estGain.toFixed(2));
}
// Adjust chart end date if user input is less than 40 weeks
if (currentGestationalAge < chartEndDate) {
labels = labels.slice(0, currentGestationalAge + 1);
recommendedGainData = recommendedGainData.slice(0, currentGestationalAge + 1);
estimatedGainData = estimatedGainData.slice(0, currentGestationalAge + 1);
}
chartInstance = new Chart(ctx, {
type: 'line',
data: {
labels: labels,
datasets: [{
label: 'Recommended Total Gain Progression',
data: recommendedGainData,
borderColor: 'rgba(0, 74, 153, 1)', // Primary color
backgroundColor: 'rgba(0, 74, 153, 0.1)',
fill: false,
tension: 0.1,
pointRadius: 1
}, {
label: 'Your Estimated Gain Progression',
data: estimatedGainData,
borderColor: 'rgba(40, 167, 69, 1)', // Success color
backgroundColor: 'rgba(40, 167, 69, 0.1)',
fill: false,
tension: 0.1,
pointRadius: 1
}]
},
options: {
responsive: true,
maintainAspectRatio: true, // Allow aspect ratio to be maintained
scales: {
x: {
title: {
display: true,
text: 'Gestational Age (Weeks)'
}
},
y: {
title: {
display: true,
text: 'Weight Gain (kg)'
},
beginAtZero: true // Start y-axis at zero
}
},
plugins: {
tooltip: {
mode: 'index',
intersect: false
},
legend: {
position: 'top'
}
},
hover: {
mode: 'index',
intersect: false
}
}
});
}
// — FAQ Toggle —
document.addEventListener('DOMContentLoaded', function() {
var faqQuestions = document.querySelectorAll('.faq-item .question');
for (var i = 0; i < faqQuestions.length; i++) {
faqQuestions[i].addEventListener('click', function() {
var answer = this.nextElementSibling;
if (answer.style.display === 'block') {
answer.style.display = 'none';
} else {
answer.style.display = 'block';
}
});
}
// Trigger initial calculation if values are pre-filled (e.g., for examples)
// Or just call calculateWeightGain() if you want it to run on load with default/example values.
});
// Initialize chart with placeholder data or calculate on load if needed
// For this example, let's call calculateWeightGain() on load to show initial state if inputs were pre-filled
// Or, just initialize with zero data if inputs are empty.
// We'll call it on load to ensure the chart renders if the user wants to see defaults.
// For a truly empty state, resetCalculator() could be called.
// Let's provide sensible defaults for the chart if inputs are empty.
window.onload = function() {
// Set default values for calculation on load if inputs are empty
if (!document.getElementById("prePregnancyWeight").value) document.getElementById("prePregnancyWeight").value = "65";
if (!document.getElementById("prePregnancyBMI").value) document.getElementById("prePregnancyBMI").value = "normal";
if (!document.getElementById("gestationalAge").value) document.getElementById("gestationalAge").value = "20";
calculateWeightGain(); // Run calculation with defaults
};