Mm Percentiles Table

Percentiles and mean in days and months for six gross motor milestones Sitting without support Percentile

Days (95% C.I.)

1st 3rd 5th 10th 25th 50th 75th 90th 95th 97th 99th

115 125 131 140 158 179 204 229 245 256 279

Mean (SD)

182 (35)

(112, 118) (123, 128) (128, 134) (138, 143) (155, 160) (177, 181) (201, 207) (225, 233) (240, 250) (251, 262) (272, 286)

Months1 (95% C.I.) 3.8 4.1 4.3 4.6 5.2 5.9 6.7 7.5 8.0 8.4 9.2

(3.7, 3.9) (4.0, 4.2) (4.2, 4.4) (4.5, 4.7) (5.1, 5.3) (5.8, 6.0) (6.6, 6.8) (7.4, 7.6) (7.9, 8.2) (8.2, 8.6) (8.9, 9.4)

6.0 (1.1)

Standing with assistance Percentile

Days (95% C.I.)

1st 3rd 5th 10th 25th 50th 75th 90th 95th 97th 99th

147 160 167 178 200 226 256 287 307 320 348

Mean (SD)

230 (43)

(144, 151) (156, 163) (164, 170) (175, 182) (197, 203) (223, 229) (253, 260) (282, 292) (301, 313) (314, 327) (339, 356)

Months1 (95% C.I.) 4.8 (4.7, 5.0) 5.2 (5.1, 5.4) 5.5 (5.4, 5.6) 5.9 (5.8, 6.0) 6.6 (6.5, 6.7) 7.4 (7.3, 7.5) 8.4 (8.3, 8.5) 9.4 (9.3, 9.6) 10.1 (9.9, 10.3) 10.5 (10.3, 10.7) 11.4 (11.1, 11.7) 7.6 (1.4)

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Percentiles and mean in days and months for six gross motor milestones Hands-and-knees crawling Percentile

Days (95% C.I.)

1st 3rd 5th 10th 25th 50th 75th 90th 95th 97th 99th

157 177 187 202 226 254 284 319 345 364 409

Mean (SD)

259 (51)

(152, 162) (172, 181) (183, 191) (198, 206) (223, 229) (250, 257) (280, 289) (313, 325) (337, 352) (355, 373) (397, 422)

Months1 (95% C.I.) 5.2 5.8 6.1 6.6 7.4 8.3 9.3 10.5 11.3 12.0 13.5

(5.0, 5.3) (5.7, 5.9) (6.0, 6.3) (6.5, 6.8) (7.3, 7.5) (8.2, 8.4) (9.2, 9.5) (10.3, 10.7) (11.1, 11.6) (11.7, 12.3) (13.0, 13.9)

8.5 (1.7)

Walking with assistance Percentile

Days (95% C.I.)

1st 3rd 5th 10th 25th 50th 75th 90th 95th 97th 99th

181 200 210 225 249 275 304 336 360 378 418

Mean (SD)

279 (45)

(176, 186) (196, 205) (206, 214) (222, 229) (246, 252) (272, 278) (300, 308) (331, 341) (353, 367) (370, 386) (407, 429)

Months1 (95% C.I.) 5.9 6.6 6.9 7.4 8.2 9.0 10.0 11.0 11.8 12.4 13.7

(5.8, 6.1) (6.4, 6.7) (6.8, 7.0) (7.3, 7.5) (8.1, 8.3) (8.9, 9.1) (9.9, 10.1) (10.9, 11.2) (11.6, 12.0) (12.1, 12.7) (13.4, 14.1)

9.2 (1.5)

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Percentiles and mean in days and months for six gross motor milestones Standing alone Percentile

Days (95% C.I.)

1st 3rd 5th 10th 25th 50th 75th 90th 95th 97th 99th

211 235 248 266 296 330 367 408 438 461 514

Mean (SD)

334 (57)

(205, 217) (230, 241) (243, 253) (262, 271) (292, 300) (326, 333) (362, 371) (401, 415) (429, 447) (451, 472) (500, 529)

Months1 (95% C.I.) 6.9 7.7 8.1 8.8 9.7 10.8 12.0 13.4 14.4 15.2 16.9

(6.7, 7.1) (7.6, 7.9) (8.0, 8.3) (8.6, 8.9) (9.6, 9.9) (10.7, 11.0) (11.9, 12.2) (13.2, 13.6) (14.1, 14.7) (14.8, 15.5) (16.4, 17.4)

11.0 (1.9)

Walking alone Percentile

Days (95% C.I.)

1st 3rd 5th 10th 25th 50th 75th 90th 95th 97th 99th

250 274 286 304 333 365 400 438 466 487 534

Mean (SD)

368 (54)

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(244, 256) (269, 279) (281, 291) (300, 309) (330, 337) (362, 369) (395, 404) (432, 444) (458, 474) (478, 497) (521, 547)

Months1 (95% C.I.) 8.2 9.0 9.4 10.0 11.0 12.0 13.1 14.4 15.3 16.0 17.6

(8.0, 8.4) (8.8, 9.2) (9.2, 9.6) (9.9, 10.1) (10.8, 11.1) (11.9, 12.1) (13.0, 13.3) (14.2, 14.6) (15.0, 15.6) (15.7, 16.3) (17.1, 18.0)

12.1 (1.8)

The calculation in months involves the division of the estimate in days by 30.4375.

Reference: WHO Multicentre Growth Reference Study Group. WHO Motor Development Study: Windows of achievement for six gross motor development milestones. Acta Paediatrica Supplement 2006;450:86-95. 3 of 3