Your activity: 251 p.v.
your limit has been reached. plz Donate us to allow your ip full access, Email: sshnevis@outlook.com

Calculator: WHO infant head circumference for age percentiles (<24 months)


Calculator: WHO infant head circumference for age percentiles (<24 months)

 
Input
 
Sex Female

Male
Age  
Head circumference  

 
Results
 
 
Z-score  
Percentile  
 
Decimal precision  

 

 

Head circumference for age percentile interpretation

 
Percentile <2: Microcephaly
Percentile ≥2 and <98: Normal head circumference
Percentile ≥98: 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.
  • 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.
  • WHO: World Health Organization.

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

 

 
Examples
 
Z-scorePercentile equivalent
- 3.0
0.3
- 2.0
2.5
+ 2.0
97.5
+ 3.0
99.7

 
References
  1. World Health Organization. The WHO Child Growth Standards. Available at: www.who.int/childgrowth/standards/en/ (Accessed on March 4, 2019).

 

LMS table: Head circumference-for-age percentiles, girls 0 to 24 months, WHO growth standards

 
Age [months] Power [L] Median [M] Variation [S]
0 1 33.8787 0.03496
1 1 36.5463 0.03210
2 1 38.2521 0.03168
3 1 39.5328 0.03140
4 1 40.5817 0.03119
5 1 41.4590 0.03102
6 1 42.1995 0.03087
7 1 42.8290 0.03075
8 1 43.3671 0.03063
9 1 43.8300 0.03053
10 1 44.2319 0.03044
11 1 44.5844 0.03035
12 1 44.8965 0.03027
13 1 45.1752 0.03019
14 1 45.4265 0.03012
15 1 45.6551 0.03006
16 1 45.8650 0.02999
17 1 46.0598 0.02993
18 1 46.2424 0.02987
19 1 46.4152 0.02982
20 1 46.5801 0.02977
21 1 46.7384 0.02972
22 1 46.8913 0.02967
23 1 47.0391 0.02962
24 1 47.1822 0.02957

 

LMS table: Head circumference-for-age percentiles, boys 0 to 24 months, WHO growth standards

 
Age [months] Power [L] Median [M] Variation [S]
0 1 34.4618 0.03686
1 1 37.2759 0.03133
2 1 39.1285 0.02997
3 1 40.5135 0.02918
4 1 41.6317 0.02868
5 1 42.5576 0.02837
6 1 43.3306 0.02817
7 1 43.9803 0.02804
8 1 44.5300 0.02796
9 1 44.9998 0.02792
10 1 45.4051 0.02790
11 1 45.7573 0.02789
12 1 46.0661 0.02789
13 1 46.3395 0.02789
14 1 46.5844 0.02791
15 1 46.8060 0.02792
16 1 47.0088 0.02795
17 1 47.1962 0.02797
18 1 47.3711 0.02800
19 1 47.5357 0.02803
20 1 47.6919 0.02806
21 1 47.8408 0.02810
22 1 47.9833 0.02813
23 1 48.1201 0.02817
24 1 48.2515 0.02821

 

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% 49.60% 49.20% 48.80% 48.40% 48.01% 47.61% 47.21% 46.81% 46.41%
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 15630 Version 9.0