Table 1 Distribution of gestational age at birth according to maternal characteristics among singleton pregnancies, Pelotas, Brazil (n = 3204)
From: Gestational age at birth and behavioral problems from four to 11 years of age: birth cohort study
Maternal characteristics | All n | <34 n (%) | 34–36 n (%) | 37+ n (%) | p-valueb |
|---|---|---|---|---|---|
Family income (MW)a | Â | Â | Â | Â | 0.002 |
 < =1 | 615 | 20 (3.3) | 94 (15.3) | 501 (81.5) |  |
 1.1–3 | 1524 | 37 (2.4) | 146 (9.6) | 1341 (88.0) |  |
 3.1–6 | 743 | 11 (1.5) | 74 (10.0) | 658 (88.6) |  |
 6.1–10 | 171 | 2 (1.2) | 15 (8.8) | 154 (90.1) |  |
 > 10 | 145 | 5 (3.5) | 12 (8.3) | 128 (88.3) |  |
Maternal schooling (years) | Â | Â | Â | Â | 0.002 |
 0 | 26 | 0 (0) | 1 (3.9) | 25 (96.2) |  |
 1–4 | 440 | 16 (3.6) | 63 (14.3) | 361 (82.1) |  |
 5–8 | 1324 | 36 (2.7) | 150 (11.3) | 1138 (86.0) |  |
 ≥ 9 | 1382 | 22 (1.6) | 125 (9.0) | 1235 (89.4) |  |
Maternal skin color | Â | Â | Â | Â | 0.007 |
 White | 2346 | 51 (2.2) | 233 (9.9) | 2062 (87.9) |  |
 Black | 642 | 22 (3.4) | 88 (13.7) | 532 (82.9) |  |
 Other | 216 | 2 (0.9) | 20 (9.3) | 194 (89.8) |  |
Single mother | Â | Â | Â | Â | 0.851 |
 Yes | 497 | 13 (2.6) | 55 (11.1) | 429 (86.3) |  |
 No | 2707 | 62 (2.3) | 286 (10.6) | 2359 (87.1) |  |
Maternal age (years) | Â | Â | Â | Â | 0.005 |
 < 20 | 604 | 21 (3.5) | 83 (13.7) | 500 (82.8) |  |
 20–34 | 2140 | 41 (1.9) | 219 (10.2) | 1880 (87.9) |  |
 > 34 | 459 | 13 (2.8) | 39 (8.5) | 407 (88.7) |  |
Parity | Â | Â | Â | Â | 0.144 |
 0 | 1266 | 34 (2.7) | 153 (12.1) | 1079 (85.2) |  |
 1 | 859 | 15 (1.8) | 85 (9.9) | 759 (88.4) |  |
 ≥ 2 | 1078 | 26 (2.4) | 103 (9.6) | 949 (88.0) |  |
Maternal smoking during pregnancy | Â | Â | Â | Â | 0.128 |
 No | 2344 | 49 (2.1) | 240 (10.2) | 2055 (87.7) |  |
 Yes | 860 | 26 (3.0) | 101 (11.7) | 733 (85.2) |  |
Type of delivery | Â | Â | Â | Â | 0.827 |
 Vaginal | 1760 | 41 (2.3) | 182 (10.3) | 1537 (87.3) |  |
 Cesarean section | 1444 | 34 (2.4) | 159 (11.0) | 1251 (86.6) |  |