 ### Description

The distribution in placental weights in Blacks and Whites were correlated with gestational age.

Measurements:

(1) weeks gestation is the number of weeks since the first day last normal menstrual period until delivery, rounded to a whole number

(2) placental weights are taken after removal of umbilical cord, membranes and blood clots

Data for Blacks

 week gestation 10th percentile 25th percentile 50th percentile 75th percentile 90th percentile 28 188 grams 213 grams 240 grams 270 grams 293 grams 29 208 232 261 291 318 30 230 255 290 321 355 31 247 275 310 350 385 32 268 296 335 378 415 33 280 313 356 398 440 34 291 330 375 419 463 35 298 343 390 438 483 36 308 356 408 455 500 37 320 368 418 468 513 38 333 380 431 480 523 39 348 390 442 490 530 40 363 400 453 498 535

10th percentile

= (0.1081002 * ((week gestation)^3)) - (11.43531 * ((week gestation)^2)) + (413.62816 * (week gestation)) - 4803.947

25th percentile

= (0.0067016 * ((week gestation)^3)) - (1.325425 * ((week gestation)^2)) + (82.329962 * (week gestation)) - 1202.135

50th percentile

= (-0.004079 * ((week gestation)^3)) - (0.381618 * ((week gestation)^2)) + (58.061522 * (week gestation)) - 999.2113

75th percentile

= (-0.025932 * ((week gestation)^3)) + (1.6136364 * ((week gestation)^2)) + (0.3436147 * (week gestation)) - 439.0512

90th percentile

= (-0.039918 * ((week gestation)^3)) + (2.6625874 * ((week gestation)^2)) - (20.8462 * (week gestation)) - 337.9613

Data for Whites

week gestation

10th percentile

25th percentile

50th percentile

75th percentile

90th percentile

28

202 grams

225 grams

254 grams

278 grams

310 grams

29

228

252

278

302

328

30

250

272

302

325

353

31

265

290

323

350

382

32

278

308

345

380

415

33

290

325

365

407