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Table 1 Distribution of birth weights for gestational age for babies born to HIV-negative women in Botswana compared with median for babies born to black women in the U.S.

From: Birth weight for gestational age norms for a large cohort of infants born to HIV-negative women in Botswana compared with norms for U.S.-born black infants

Gestational Age (weeks) N Minimum (grams) Lower Quartile (grams) Median (grams) Upper Quartile (grams) Maximum (grams) U.S. median * (grams) Δ Median (Botswana - U.S.) p-value
26 9 700 880 930 1230 1680 857 73 .051
27 20 670 1013 1116 1610 2310 977 139 .004
28 29 790 1120 1260 1740 2700 1120 140 .003
29 54 750 1200 1375 1725 2950 1304 71 .015
30 62 860 1390 1660 2180 2990 1525 135 .002
31 71 810 1535 1815 2630 3300 1804 11 .032
32 119 800 1680 2085 2730 3440 2084 0.6 .099
33 162 1170 2055 2410 2790 3790 2358 52 .370
34 268 1380 2100 2510 2928 3850 2571 - 61 .095
35 394 1180 2320 2700 3060 4200 2733 - 33 .172
36 687 1470 2560 2850 3115 4335 2870 - 20 .164
37 1056 1790 2690 2960 3240 4680 3014 - 53 < .001
38 1758 1900 2820 3060 3330 4550 3158 - 98 < .001
39 2340 1890 2890 3130 3405 5150 3277 - 147 < .001
40 2482 1960 2970 3220 3500 4920 3356 - 135 < .001
41 1357 1980 3000 3290 3600 5000 3399 - 109 < .001
42 746 2000 3000 3300 3610 5080 3346 - 45 .016
43 125 2300 3000 3280 3540 4405 3316 - 35 .492
44 14 2680 3100 3345 3700 4785 3328 16 .583
  1. * Oken E, Kleinman KP, Rich-Edwards J, Gillman MW. A nearly continuous measure of birth weight for gestational age using a United States national reference. BMC Pediatrics 2003;3:10.
  2. Wilcoxon signed rank test.