# Preterm Infant Growth Chart Calculator

## 23-41 Weeks: Weight For Age Percentile

### Description:

This app uses tables and data solely based on United States premature babies. Caution should be used on all charts for the twenty-third week for percentiles at or below the 3rd percentile and at or above the 97th percentile. This is due to a low population size. For the twenty-fourth week, the data is skewed to the left for all head circumference data. See the reference below for more information.

This calculator provides your baby's weight percentile based on age. The percentile shows how your infant's weight compares to other infants. The percentile tells you what percentage of babies weigh less than your baby. For example out of a sample of 100 babies, a percentile value of 40 percent means your baby weighs more than 40 babies and weighs less than the other 60 babies.

A percentile of 50% represents the average or mean weight. A value below 50 percent means a baby weighs less than the average. A value greater than 50 percent means a baby is above average. This does not mean your baby is overweight or underweight. A doctor or physician should be consulted to determine weight status.

### Calculation Instructions:

1. Select Gender - Choose male for boys and female for girls.
2. Measure Date - Enter the day the measurement was taken.
3. Due Date - Enter the original due date. Note, this calculator assume 280 days between first day of last menstrual period (LMP) to birth.
4. Enter Head Circumference - distance around the child's head.
5. Select Units
• cm - Metric centimeters
• in - Standard inch

### Outputs:

1. Percentile - The weight percentile of the child.
2. Gestational Age - The time period from the first day of LMP to the measure date in weeks
3. Weight - The mass of the child in metric and standard units.
4. Graph Plot - Weight versus age graph with 5, 10, 25, 50, 75, 95 and calculated percentile lines.

### Reference:

Olsen, Irene E, Sue A. Groveman, M. Louise Lawson, Reese H. Clark and Babette S. Zemel. "New Intrauterine Growth Curves Based on United States Data". Pediatrics 25 January 2010. Print.

### CDC Recommended Growth Charts:

The United States Center for Disease Control (CDC) recommends using the World Health Organization (WHO) charts for the first two year of life (0 to 2 years). After two years, it is recommended to return to the CDC charts.