Enter Baby Growth Details
The page uses a single-column flow, while the calculator fields switch to 3 columns on large screens, 2 on medium, and 1 on mobile.
Example Data Table
| Input or Output | Sample Value | Explanation |
|---|---|---|
| Sex | Male | Reference curves switch by sex. |
| Gestational Age at Birth | 32 wk 4 d | Baby was born 7 weeks 3 days early. |
| Birth Weight | 1.85 kg | Used to estimate average daily weight gain. |
| Current Weight | 3.25 kg | Compared with the interpolated corrected-age reference median. |
| Corrected Age | 2 wk 4 d | Chronological age minus the weeks born early. |
| Average Weight Gain | 20.0 g/day | Useful for quick catch-up screening between visits. |
| Estimated Weight Percentile | 22.4 | Screening estimate only, not a formal diagnosis. |
| Projected 4 Week Weight | 3.95 kg | Based on the midpoint of the suggested gain range. |
Formula Used
1) Prematurity days: (40 × 7) − gestational age at birth in days
2) Chronological age: assessment date − birth date
3) Corrected age: chronological age − prematurity days
4) Postmenstrual age: gestational age at birth in days + chronological age in days
5) Average weight gain: ((current weight − birth weight) × 1000) ÷ chronological days
6) Length velocity: (current length − birth length) ÷ chronological weeks
7) Head growth velocity: (current head circumference − birth head circumference) ÷ chronological weeks
8) BMI: weight in kg ÷ (length in meters)²
9) Weight-for-length: (weight in grams) ÷ length in cm
10) Estimated percentile: the calculator interpolates a sex-specific corrected-age median, estimates a standard deviation, then converts the z-score to a percentile. This is a screening shortcut for home tracking and should not replace neonatal follow-up charts.
How to Use This Calculator
- Choose the baby’s sex.
- Enter gestational age at birth in weeks and days.
- Enter the birth date and the date of the current measurement.
- Fill in birth and current weight values.
- Fill in birth and current length values.
- Fill in birth and current head circumference values.
- Click Calculate Growth to show results above the form.
- Review corrected age, gain velocity, percentiles, and the graph.
- Use the CSV or PDF buttons to save the screening summary.
- Share the saved summary with your pediatric clinician when needed.
FAQs
1) What is corrected age?
Corrected age subtracts the weeks a baby was born early from chronological age. It helps compare growth to the due date rather than the birth date during early follow-up.
2) Why is corrected age important for preterm babies?
Preterm babies start outside the usual full-term timeline. Corrected age gives a fairer view of catch-up growth, feeding progress, and developmental expectations during infancy.
3) How long is corrected age usually used?
Many clinicians use corrected age through at least the first year, and sometimes up to two years, depending on gestation, medical history, and ongoing growth concerns.
4) Does a low percentile always mean something is wrong?
No. A low percentile can still be acceptable if growth stays consistent and the baby is clinically well. What matters most is pattern, velocity, feeding, and medical context.
5) Why include head circumference?
Head circumference helps screen brain and skull growth trends. In preterm follow-up, it is often reviewed alongside weight and length to understand overall growth quality.
6) Are these percentiles exact clinical chart values?
No. They are interpolated screening estimates designed for practical home monitoring. Formal charting in clinic is more precise and may use different reference systems.
7) When should I seek medical advice quickly?
Call your pediatric team if feeding drops, weight gain stalls, vomiting increases, breathing worsens, urine decreases, or head and body growth appear to flatten suddenly.
8) Can I enter pounds or inches?
This version uses kilograms and centimeters for cleaner calculations. Convert other units first so the gain, BMI, and percentile estimates remain consistent.