Your activity: 166 p.v.
your limit has been reached. plz Donate us to allow your ip full access, Email: sshnevis@outlook.com

Calculator: CDC/NCHS infant head circumference for age percentiles (<36 months)


Calculator: CDC/NCHS infant head circumference for age percentiles (<36 months)

 
Input
 
Sex Female

Male
Age  
Head circumference  

 
Results
 
Important: Inputs must be complete to perform calculation.

 
 
Z-score  
Percentile  
 
Decimal precision  

 

 

Head circumference for age percentile interpretation

 
Percentile <3: Microcephaly
Percentile ≥3 and <97: Normal head circumference
Percentile ≥97: Macrocephaly

 
 

 
Notes
  • Microcephaly is a Head circumference greater than 2 standard deviations below the mean.
  • Macrocephaly is a Head circumference greater than 2 standard deviations above the mean.
  • CDC/NCHS: United States Centers for Disease Control/National Center for Health Statistics.
  • At the extremes (>97th percentile or <3rd percentile), small differences in percentiles represent clinically important differences. At these extremes, the Z-score is a more precise reflection of how far the measurement deviates from the mean and is a useful tool for tracking changes.
  • The accuracy of the calculation can be assessed by viewing the graph of head circumference-for-age percentiles for this sex and age group in UpToDate.
  • For all LMS tables, the row in the table corresponding to the patient-specific value is found in the first column of the table; values to be used for L (the Box-Cox power), M (the median), and S (the generalized coefficient of variation) in the equation for Z-score are retrieved.
  • Z-scores may be used to do a table lookup for the corresponding percentile in the Normal table percentiles for Z-score table (below). Numbers along the left side (Y-axis) of the table represent the first number and first decimal place of the Z-score, while the numbers along the top (X-axis) of the table represent the second decimal position of the Z-score.

 
Equations used
 
Z-score = ((Head_circumference/M)L - 1) / (L * S)
Percentile = ZtoPercentile(Z-score)

 

 
Examples
 
Z-scorePercentile equivalent
- 2.0
2.5
+ 2.0
97.5
+ 3.0
99.7

 
References
  1. Centers for Disease Control and Prevention, National Center for Health Statistics. Clinical growth charts. Available at: https://www.cdc.gov/growthcharts/clinical_charts.htm (Accessed on May 6, 2021).

 

LMS table: Head circumference-for-age percentiles, girls birth to 36 months, CDC growth charts

 
Age [months] Power [L] Median [M] Variation [S]
0.5 -1.440271514 36.03453876 0.042999604
1.5 -1.581016348 37.97671987 0.038067862
2.5 -1.593136386 39.3801263 0.035079612
3.5 -1.521492427 40.46773733 0.033096443
4.5 -1.394565915 41.34841008 0.03170963
5.5 -1.231713389 42.0833507 0.030709039
6.5 -1.046582628 42.71033603 0.029974303
7.5 -0.848932692 43.25428882 0.029430992
8.5 -0.645779124 43.73249646 0.029030379
9.5 -0.442165412 44.15742837 0.028739112
10.5 -0.24163206 44.53836794 0.028533537
11.5 -0.046673786 44.88240562 0.028396382
12.5 0.141031094 45.19507651 0.028314722
13.5 0.320403169 45.48078147 0.028278682
14.5 0.490807133 45.74307527 0.028280585
15.5 0.65193505 45.98486901 0.028314363
16.5 0.803718086 46.20857558 0.028375159
17.5 0.946259679 46.41621635 0.028459033
18.5 1.079784984 46.60950084 0.028562759
19.5 1.204602687 46.78988722 0.028683666
20.5 1.321076285 46.95862881 0.028819525
21.5 1.429602576 47.11681039 0.028968459
22.5 1.530595677 47.26537682 0.029128879
23.5 1.624475262 47.40515585 0.029299426
24.5 1.71165803 47.53687649 0.029478937
25.5 1.792551616 47.66118396 0.029666406
26.5 1.867550375 47.77865186 0.02986096
27.5 1.93703258 47.8897923 0.030061839
28.5 2.001358669 47.99506422 0.030268375
29.5 2.060870301 48.09488048 0.030479985
30.5 2.115889982 48.18961365 0.03069615
31.5 2.16672113 48.2796011 0.030916413
32.5 2.21364844 48.36514917 0.031140368
33.5 2.256943216 48.44653703 0.031367651
34.5 2.296844024 48.52401894 0.031597939
35.5 2.333589434 48.59782828 0.031830942

 

LMS table: Head circumference-for-age percentiles, boys birth to 36 months, CDC growth charts

 
Age [months] Power [L] Median [M] Variation [S]
0.5 4.310927464 37.19361054 0.047259148
1.5 3.869576802 39.20742929 0.040947903
2.5 3.305593039 40.65233195 0.037027722
3.5 2.720590297 41.76516959 0.034364245
4.5 2.16804824 42.66116148 0.032462175
5.5 1.675465689 43.40488731 0.031064702
6.5 1.255160322 44.03609923 0.03002267
7.5 0.91054114 44.58096912 0.029242173
8.5 0.639510474 45.05761215 0.028660454
9.5 0.436978864 45.4790756 0.0282336
10.5 0.296275856 45.85505706 0.027929764
11.5 0.210107251 46.19295427 0.027725179
12.5 0.171147024 46.49853438 0.027601686
13.5 0.172393886 46.77637684 0.027545148
14.5 0.207371541 47.03017599 0.027544382
15.5 0.270226126 47.2629533 0.027590417
16.5 0.355757274 47.47720989 0.02767598
17.5 0.459407627 47.67503833 0.027795115
18.5 0.577227615 47.85820606 0.0279429
19.5 0.705826778 48.02821867 0.028115241
20.5 0.842319055 48.18636864 0.028308707
21.5 0.984266833 48.3337732 0.028520407
22.5 1.129626698 48.47140432 0.028747896
23.5 1.276691223 48.60011223 0.028989089
24.5 1.424084853 48.72064621 0.029242207
25.5 1.570621291 48.83366629 0.029505723
26.5 1.715393998 48.93976089 0.029778323
27.5 1.857652984 49.03945383 0.030058871
28.5 1.996810563 49.13321432 0.030346384
29.5 2.132411346 49.22146409 0.030640006
30.5 2.264111009 49.30458348 0.030938992
31.5 2.391658052 49.38291658 0.031242693
32.5 2.514878222 49.45677569 0.031550537
33.5 2.633661226 49.526445 0.031862026
34.5 2.747949445 49.59218385 0.03217672
35.5 2.857728375 49.65422952 0.032494231

 

LMS table: Normal table percentiles for Z-score

 
Z 0 1 2 3 4 5 6 7 8 9
-3.0 0.13% 0.13% 0.13% 0.12% 0.12% 0.11% 0.11% 0.11% 0.10% 0.10%
-2.9 0.19% 0.18% 0.18% 0.17% 0.16% 0.16% 0.15% 0.15% 0.14% 0.14%
-2.8 0.26% 0.25% 0.24% 0.23% 0.23% 0.22% 0.21% 0.21% 0.20% 0.19%
-2.7 0.35% 0.34% 0.33% 0.32% 0.31% 0.30% 0.29% 0.28% 0.27% 0.26%
-2.6 0.47% 0.45% 0.44% 0.43% 0.41% 0.40% 0.39% 0.38% 0.37% 0.36%
-2.5 0.62% 0.60% 0.59% 0.57% 0.55% 0.54% 0.52% 0.51% 0.49% 0.48%
-2.4 0.82% 0.80% 0.78% 0.75% 0.73% 0.71% 0.70% 0.68% 0.66% 0.64%
-2.3 1.07% 1.04% 1.02% 0.99% 0.96% 0.94% 0.91% 0.89% 0.87% 0.84%
-2.2 1.39% 1.36% 1.32% 1.29% 1.26% 1.22% 1.19% 1.16% 1.13% 1.10%
-2.1 1.79% 1.74% 1.70% 1.66% 1.62% 1.58% 1.54% 1.50% 1.46% 1.43%
-2.0 2.28% 2.22% 2.17% 2.12% 2.07% 2.02% 1.97% 1.92% 1.88% 1.83%
-1.9 2.87% 2.81% 2.74% 2.68% 2.62% 2.56% 2.50% 2.44% 2.39% 2.33%
-1.8 3.59% 3.52% 3.44% 3.36% 3.29% 3.22% 3.14% 3.07% 3.01% 2.94%
-1.7 4.46% 4.36% 4.27% 4.18% 4.09% 4.01% 3.92% 3.84% 3.75% 3.67%
-1.6 5.48% 5.37% 5.26% 5.16% 5.05% 4.95% 4.85% 4.75% 4.65% 4.55%
-1.5 6.68% 6.55% 6.43% 6.30% 6.18% 6.06% 5.94% 5.82% 5.71% 5.59%
-1.4 8.08% 7.93% 7.78% 7.64% 7.49% 7.35% 7.22% 7.08% 6.94% 6.81%
-1.3 9.68% 9.51% 9.34% 9.18% 9.01% 8.85% 8.69% 8.53% 8.38% 8.23%
-1.2 11.51% 11.31% 11.12% 10.94% 10.75% 10.57% 10.38% 10.20% 10.03% 9.85%
-1.1 13.57% 13.35% 13.14% 12.92% 12.71% 12.51% 12.30% 12.10% 11.90% 11.70%
-1.0 15.87% 15.63% 15.39% 15.15% 14.92% 14.69% 14.46% 14.23% 14.01% 13.79%
-0.9 18.41% 18.14% 17.88% 17.62% 17.36% 17.11% 16.85% 16.60% 16.35% 16.11%
-0.8 21.19% 20.90% 20.61% 20.33% 20.05% 19.77% 19.49% 19.22% 18.94% 18.67%
-0.7 24.20% 23.89% 23.58% 23.27% 22.97% 22.66% 22.36% 22.07% 21.77% 21.48%
-0.6 27.43% 27.09% 26.76% 26.44% 26.11% 25.79% 25.46% 25.14% 24.83% 24.51%
-0.5 30.85% 30.50% 30.15% 29.81% 29.46% 29.12% 28.77% 28.43% 28.10% 27.76%
-0.4 34.46% 34.09% 33.72% 33.36% 33.00% 32.64% 32.28% 31.92% 31.56% 31.21%
-0.3 38.21% 37.83% 37.45% 37.07% 36.69% 36.32% 35.94% 35.57% 35.20% 34.83%
-0.2 42.07% 41.68% 41.29% 40.91% 40.52% 40.13% 39.74% 39.36% 38.97% 38.59%
-0.1 46.02% 45.62% 45.22% 44.83% 44.43% 44.04% 43.64% 43.25% 42.86% 42.47%
0.0 50.00% 50.40% 50.80% 51.20% 51.60% 51.99% 52.39% 52.79% 53.19% 53.59%
0.1 53.98% 54.38% 54.78% 55.17% 55.57% 55.96% 56.36% 56.75% 57.14% 57.54%
0.2 57.93% 58.32% 58.71% 59.10% 59.48% 59.87% 60.26% 60.64% 61.03% 61.41%
0.3 61.79% 62.17% 62.55% 62.93% 63.31% 63.68% 64.06% 64.43% 64.80% 65.17%
0.4 65.54% 65.91% 66.28% 66.64% 67.00% 67.36% 67.72% 68.08% 68.44% 68.79%
0.5 69.15% 69.50% 69.85% 70.19% 70.54% 70.88% 71.23% 71.57% 71.90% 72.24%
0.6 72.58% 72.91% 73.24% 73.57% 73.89% 74.22% 74.54% 74.86% 75.18% 75.49%
0.7 75.80% 76.12% 76.42% 76.73% 77.04% 77.34% 77.64% 77.94% 78.23% 78.52%
0.8 78.81% 79.10% 79.39% 79.67% 79.96% 80.23% 80.51% 80.79% 81.06% 81.33%
0.9 81.59% 81.86% 82.12% 82.38% 82.64% 82.89% 83.15% 83.40% 83.65% 83.89%
1.0 84.13% 84.38% 84.61% 84.85% 85.08% 85.31% 85.54% 85.77% 85.99% 86.21%
1.1 86.43% 86.65% 86.86% 87.08% 87.29% 87.49% 87.70% 87.90% 88.10% 88.30%
1.2 88.49% 88.69% 88.88% 89.07% 89.25% 89.44% 89.62% 89.80% 89.97% 90.15%
1.3 90.32% 90.49% 90.66% 90.82% 90.99% 91.15% 91.31% 91.47% 91.62% 91.77%
1.4 91.92% 92.07% 92.22% 92.36% 92.51% 92.65% 92.79% 92.92% 93.06% 93.19%
1.5 93.32% 93.45% 93.57% 93.70% 93.82% 93.94% 94.06% 94.18% 94.30% 94.41%
1.6 94.52% 94.63% 94.74% 94.85% 94.95% 95.05% 95.15% 95.25% 95.35% 95.45%
1.7 95.54% 95.64% 95.73% 95.82% 95.91% 95.99% 96.08% 96.16% 96.25% 96.33%
1.8 96.41% 96.49% 96.56% 96.64% 96.71% 96.78% 96.86% 96.93% 97.00% 97.06%
1.9 97.13% 97.19% 97.26% 97.32% 97.38% 97.44% 97.50% 97.56% 97.62% 97.67%
2.0 97.73% 97.78% 97.83% 97.88% 97.93% 97.98% 98.03% 98.08% 98.12% 98.17%
2.1 98.21% 98.26% 98.30% 98.34% 98.38% 98.42% 98.46% 98.50% 98.54% 98.57%
2.2 98.61% 98.65% 98.68% 98.71% 98.75% 98.78% 98.81% 98.84% 98.87% 98.90%
2.3 98.93% 98.96% 98.98% 99.01% 99.04% 99.06% 99.09% 99.11% 99.13% 99.16%
2.4 99.18% 99.20% 99.22% 99.25% 99.27% 99.29% 99.31% 99.32% 99.34% 99.36%
2.5 99.38% 99.40% 99.41% 99.43% 99.45% 99.46% 99.48% 99.49% 99.51% 99.52%
2.6 99.53% 99.55% 99.56% 99.57% 99.59% 99.60% 99.61% 99.62% 99.63% 99.64%
2.7 99.65% 99.66% 99.67% 99.68% 99.69% 99.70% 99.71% 99.72% 99.73% 99.74%
2.8 99.74% 99.75% 99.76% 99.77% 99.77% 99.78% 99.79% 99.80% 99.80% 99.81%
2.9 99.81% 99.82% 99.83% 99.83% 99.84% 99.84% 99.85% 99.85% 99.86% 99.86%
3.0 99.87% 99.87% 99.87% 99.88% 99.88% 99.89% 99.89% 99.89% 99.90% 99.90%
Only digits 0 to 9 and a single decimal point (".") are acceptable as numeric inputs. Attempted input of other characters into a numeric field may lead to an incorrect result.

Information on this page may not appear correctly if printed.

Legal Notices and Disclaimer

All information contained in and produced by the EBMcalc system is provided for educational purposes only. This information should not be used for the diagnosis or treatment of any health problem or disease. THIS INFORMATION IS NOT INTENDED TO REPLACE CLINICAL JUDGMENT OR GUIDE INDIVIDUAL PATIENT CARE IN ANY MANNER. Click here for full notice and disclaimer.

EBMcalc is Copyright © 1998-2023 Foundation Internet Services, LLC

Topic 13417 Version 18.0