Table 1 Descriptive statistics for birth weight, small for gestational age and preterm births by socio-demographics and mother characteristics among all singleton births born in Eastern Massachusetts between 1996 and 2002
Categorical variables | All births (% of total) | Mean birth weight (in grams) (SD) | Small for gestational age N (%) | Preterm birth N (%) | Comparison group (≥ 37 weeks; ≥ 2500 grams) N (%) | ||||
|---|---|---|---|---|---|---|---|---|---|
Mother race | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   White | 75.3 | 3463 | (545) | 32103 | 76.2 | 22160 | 66.8 | 266329 | 76.0 |
   African-American | 7.4 | 3236 | (638) | 2938 | 7.0 | 3994 | 12.0 | 24530 | 7.0 |
   Asian | 6.0 | 3241 | (510) | 2471 | 5.9 | 2194 | 6.6 | 20900 | 6.0 |
   Hispanic | 11.0 | 3306 | (565) | 4531 | 10.8 | 4730 | 14.3 | 37691 | 10.8 |
   Native American | 0.2 | 3371 | (581) | 66 | 0.2 | 68 | 0.2 | 537 | 0.2 |
   Missing | 0.1 | 3426 | (622) | 0 | 0 | 38 | 0.1 | 417 | 0.1 |
Mother education | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   Primary and secondary (≤ 8 years) | 2.6 | 3296 | (561) | 1307 | 3.1 | 1126 | 3.4 | 8073 | 2.3 |
   High school (>8 – 12 years) | 29.0 | 3338 | (576) | 15190 | 36.1 | 11453 | 34.5 | 96981 | 27.7 |
   Some college (13 – 15 years) | 39.9 | 3481 | (533) | 13354 | 31.7 | 11012 | 33.2 | 145698 | 41.6 |
   College or postgraduate | 22.6 | 3433 | (562) | 9118 | 21.7 | 7269 | 21.9 | 79975 | 22.8 |
   (≥ 16 years) |  |  |  |  |  |  |  |  |  |
   Missing | 5.9 | 3333 | (573) | 3140 | 7.5 | 2324 | 7.0 | 19677 | 5.6 |
APNCU | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   None | 0.6 | 3267 | (714) | 251 | 0.6 | 337 | 1.0 | 1825 | 0.5 |
   Inadequate | 7.8 | 3308 | (571) | 4511 | 10.7 | 3147 | 9.5 | 25652 | 7.3 |
   Intermediate | 8.0 | 3487 | (509) | 3842 | 9.1 | 1036 | 3.1 | 28985 | 8.3 |
   Appropriate | 48.1 | 3507 | (487) | 20185 | 47.9 | 3263 | 9.8 | 181619 | 51.8 |
   Appropriate plus | 35.5 | 3301 | (627) | 13320 | 31.6 | 25401 | 76.5 | 112323 | 32.1 |
Mother age at birth | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   <20 | 8.9 | 3246 | (565) | 5616 | 13.3 | 4020 | 12.1 | 28308 | 8.1 |
   20 – 29 | 36.6 | 3389 | (550) | 16783 | 39.9 | 12007 | 36.2 | 127149 | 36.3 |
   30 – 34 | 33.7 | 3465 | (546) | 12143 | 28.8 | 10017 | 30.2 | 121240 | 34.6 |
   35 – 39 | 17.4 | 3462 | (574) | 6196 | 14.7 | 5762 | 17.4 | 61997 | 17.7 |
   >39 | 3.4 | 3422 | (600) | 1371 | 3.3 | 1378 | 4.2 | 11710 | 3.3 |
Number of cigarettes smoked during pregnancy (per day) | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   None | 90.0 | 3438 | (555) | 33410 | 79.3 | 29001 | 87.4 | 320511 | 91.5 |
   Any amount | 9.8 | 3208 | (558) | 8655 | 20.6 | 4115 | 12.4 | 29301 | 8.4 |
   Missing | 0.2 | 3369 | (648) | 44 | 0.1 | 68 | 0.2 | 592 | 0.2 |
Number of cigarettes smoked before pregnancy (per day) | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   None | 83.0 | 3437 | (556) | 30580 | 72.6 | 26896 | 81.1 | 295766 | 84.4 |
   Any amount | 16.6 | 3309 | (566) | 11398 | 27.1 | 6120 | 18.4 | 53238 | 15.2 |
   Missing | 0.4 | 3384 | (620) | 131 | 0.3 | 168 | 0.5 | 1400 | 0.4 |
Previous infant ≥ 4000 grams |  |  |  |  |  |  |  |  |  |
   None | 98.6 | 3411 | (556) | 41851 | 99.4 | 32730 | 98.6 | 344956 | 98.4 |
   Yes | 0.9 | 3938 | (546) | 63 | 0.1 | 175 | 0.5 | 3626 | 1.0 |
   Missing | 0.5 | 3355 | (712) | 195 | 0.5 | 279 | 0.8 | 1822 | 0.5 |
Previous preterm birth | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   None | 98.6 | 3419 | (556) | 41256 | 98.0 | 31946 | 96.3 | 346553 | 98.9 |
   Yes | 0.9 | 3011 | (678) | 658 | 1.6 | 959 | 2.9 | 2029 | 0.6 |
   Missing | 0.5 | 3355 | (712) | 195 | 0.5 | 279 | 0.8 | 1822 | 0.5 |
Gender of infant | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   Male | 51.2 | 3473 | (572) | 21631 | 51.4 | 18172 | 54.8 | 178071 | 50.8 |
   Female | 48.8 | 3355 | (540) | 20478 | 48.6 | 15012 | 45.2 | 172333 | 49.2 |