TABLE 2.
A priori potential risk factors by sex and preterm birth status.a
| Male preterm | Female preterm | Male term | Female term | ||
|---|---|---|---|---|---|
|
|
|
|
|
||
| Defect | Characteristic | nb (%*) | nb (%) | nb (%) | nb (%) |
| Spina bifida | Folic acid-containing supplement usec | ||||
| Yes | 95 (10.8) | 111 (12.7) | 337 (38.5) | 333 (38.0) | |
| No | 50 (17.2) | 29 (10.0) | 118 (40.5) | 94 (32.3) | |
| Maternal smokingc | |||||
| Yes | 26 (12.6) | 32 (15.5) | 74 (35.7) | 75 (36.2) | |
| No | 121 (12.5) | 111 (11.4) | 386 (39.8) | 353 (36.4) | |
| Pre-pregnancy body mass index | |||||
| <30 kg/m2 | 114 (13.8) | 99 (11.9) | 321 (38.7) | 295 (35.6) | |
| ≥30 kg/m2 | 27 (9.3) | 37 (12.8) | 114 (39.5) | 111 (38.4) | |
| Interpregnancy interval | |||||
| No previous pregnancies | 38 (12.4) | 32 (10.5) | 131 (42.8) | 105 (34.3) | |
| ≤12 months | 43 (17.1) | 33 (13.1) | 79 (31.4) | 97 (38.5) | |
| >12 months | 66 (10.8) | 72 (11.8) | 246 (40.3) | 227 (37.2) | |
| Total | 150 (12.5) | 145 (12.0) | 470 (39.0) | 439 (36.5) | |
| D-transposition of the great arteries | Folic acid-containing supplement usec | ||||
| Yes | 34 (6.2) | 15 (2.7) | 348 (63.4) | 152 (27.7) | |
| No | 9 (5.4) | 6 (3.6) | 108 (64.3) | 45 (26.8) | |
| Maternal smokingc | |||||
| Yes | 5 (3.7) | 8 (5.8) | 90 (65.7) | 34 (24.8) | |
| No | 39 (6.7) | 13 (2.2) | 371 (63.8) | 159 (27.3) | |
| Pre-pregnancy body mass index | |||||
| <30 kg/m2 | 34 (5.8) | 21 (3.6) | 372 (63.6) | 158 (27.0) | |
| ≥30 kg/m2 | 6 (5.0) | 1 (0.8) | 81 (67.5) | 32 (26.7) | |
| Interpregnancy interval | |||||
| No previous pregnancies | 12 (5.7) | 6 (2.9) | 126 (60.3) | 65 (31.1) | |
| ≤12 months | 8 (6.2) | 9 (6.9) | 83 (63.9) | 30 (23.1) | |
| >12 months | 22 (6.0) | 6 (2.9) | 245 (66.2) | 97 (26.2) | |
| Total | 44 (6.0) | 23 (3.1) | 466 (63.7) | 199 (27.2) | |
| Tetralogy of Fallot | Folic acid-containing supplement usec | ||||
| Yes | 86 (10.0) | 70 (8.1) | 408 (47.3) | 298 (34.6) | |
| No | 20 (9.2) | 18 (8.3) | 121 (55.5) | 59 (27.1) | |
| Maternal smokingc | |||||
| Yes | 17 (9.6) | 17 (9.6) | 83 (46.9) | 60 (33.9) | |
| No | 89 (9.9) | 69 (7.7) | 446 (49.5) | 297 (33.0) | |
| Pre-pregnancy body mass index | |||||
| <30 kg/m2 | 82 (9.8) | 66 (7.9) | 407 (48.8) | 279 (33.5) | |
| ≥30 kg/m2 | 21 (9.5) | 19 (8.6) | 108 (48.9) | 73 (33.0) | |
| Interpregnancy interval | |||||
| No previous pregnancies | 49 (13.7) | 30 (8.4) | 166 (46.5) | 112 (31.4) | |
| ≤12 months | 16 (8.2) | 17 (8.7) | 91 (46.7) | 71 (36.4) | |
| >12 months | 40 (7.9) | 39 (7.7) | 266 (52.3) | 164 (32.2) | |
| Total | 110 (10.0) | 90 (8.2) | 540 (49.0) | 362 (32.8) | |
| Cleft palate without cleft lip | Folic acid-containing supplement usec | ||||
| Yes | 90 (7.8) | 96 (8.4) | 408 (35.5) | 555 (48.3) | |
| No | 20 (6.1) | 28 (8.5) | 116 (35.3) | 165 (50.2) | |
| Maternal smokingc | |||||
| Yes | 29 (9.0) | 28 (8.7) | 115 (35.8) | 149 (46.4) | |
| No | 86 (7.4) | 99 (8.5) | 412 (35.4) | 567 (48.7) | |
| Pre-pregnancy body mass index | |||||
| <30 kg/m2 | 99 (8.4) | 105 (8.9) | 418 (35.3) | 563 (47.5) | |
| ≥30 kg/m2 | 13 (4.8) | 23 (8.5) | 101 (37.1) | 135 (49.6) | |
| Interpregnancy interval | |||||
| No previous pregnancies | 41 (10.0) | 38 (9.3) | 142 (34.7) | 188 (46.0) | |
| ≤12 months | 27 (9.3) | 27 (9.3) | 121 (41.7) | 115 (39.7) | |
| >12 months | 47 (6.2) | 59 (7.7) | 255 (33.4) | 402 (52.7) | |
| Total | 117 (7.7) | 131 (8.6) | 536 (35.3) | 733 (48.3) | |
| Cleft lip ± cleft palate | Folic acid-containing supplement usec | ||||
| Yes | 201 (9.1) | 96 (4.4) | 1257 (57.0) | 651 (29.5) | |
| No | 64 (9.4) | 24 (3.5) | 375 (55.3) | 215 (31.7) | |
| Maternal smokingc | |||||
| Yes | 57 (8.4) | 28 (4.1) | 385 (56.9) | 207 (30.6) | |
| No | 204 (9.3) | 93 (4.2) | 1241 (56.5) | 659 (30.0) | |
| Pre-pregnancy body mass index | |||||
| <30 kg/m2 | 205 (9.1) | 94 (4.2) | 1280 (57.0) | 665 (29.6) | |
| ≥30 kg/m2 | 51 (9.7) | 23 (4.4) | 294 (55.8) | 159 (30.2) | |
| Interpregnancy interval | |||||
| No previous pregnancies | 89 (10.4) | 42 (4.9) | 491 (57.2) | 236 (27.5) | |
| ≤12 months | 43 (7.8) | 24 (4.3) | 299 (53.9) | 189 (34.1) | |
| >12 months | 125 (8.8) | 51 (3.6) | 822 (57.9) | 423 (29.8) | |
| Total | 267 (9.1) | 123 (4.2) | 1664 (56.8) | 876 (29.9) | |
| Longitudinal/intercalary limb deficiency | Folic acid-containing supplement usec | ||||
| Yes | 41 (11.7) | 35 (10.0) | 161 (45.9) | 114 (32.5) | |
| No | 12 (11.4) | 16 (15.2) | 43 (41.0) | 34 (32.4) | |
| Maternal smokingc | |||||
| Yes | 9 (9.2) | 14 (14.3) | 39 (39.8) | 36 (36.7) | |
| No | 43 (12.2) | 36 (10.2) | 163 (46.1) | 112 (31.6) | |
| Pre-pregnancy body mass index | |||||
| <30 kg/m2 | 42 (11.6) | 35 (9.7) | 164 (45.3) | 121 (33.4) | |
| ≥30 kg/m2 | 12 (14.8) | 13 (16.1) | 30 (37.0) | 26 (32.1) | |
| Interpregnancy interval | |||||
| No previous pregnancies | 24 (15.1) | 20 (12.6) | 67 (42.1) | 48 (30.2) | |
| ≤12 months | 6 (6.7) | 8 (9.0) | 49 (55.1) | 26 (29.2) | |
| >12 months | 22 (11.0) | 22 (11.0) | 83 (41.3) | 74 (36.8) | |
| Total | 54 (11.6) | 52 (11.2) | 208 (44.7) | 151 (32.5) | |
| Transverse limb deficiency | Folic acid-containing supplement usec | ||||
| Yes | 56 (11.2) | 47 (9.4) | 213 (42.4) | 186 (37.1) | |
| No | 18 (12.1) | 10 (6.7) | 73 (49.0) | 48 (32.2) | |
| Maternal smokingc | |||||
| Yes | 17 (13.0) | 13 (9.9) | 49 (37.4) | 52 (39.7) | |
| No | 55 (10.6) | 42 (8.1) | 238 (45.7) | 186 (35.7) | |
| Pre-pregnancy body mass index | |||||
| <30 kg/m2 | 60 (11.7) | 47 (9.2) | 219 (42.8) | 186 (36.3) | |
| ≥30 kg/m2 | 11 (9.4) | 8 (6.8) | 55 (47.0) | 43 (36.8) | |
| Interpregnancy interval | |||||
| No previous pregnancies | 32 (14.7) | 19 (8.7) | 89 (40.8) | 78 (35.8) | |
| ≤12 months | 14 (13.0) | 10 (9.3) | 52 (48.2) | 32 (29.6) | |
| >12 months | 28 (8.6) | 26 (8.0) | 147 (45.0) | 126 (38.5) | |
| Total | 76 (11.4) | 57 (8.5) | 293 (43.9) | 241 (36.1) | |
| Craniosynostosis | Folic acid-containing supplement usec | ||||
| Yes | 95 (7.8) | 39 (3.2) | 745 (61.1) | 341 (28.0) | |
| No | 21 (8.4) | 11 (4.4) | 131 (52.6) | 86 (34.5) | |
| Maternal smokingc | |||||
| Yes | 20 (7.9) | 13 (5.2) | 150 (59.5) | 69 (27.4) | |
| No | 97 (7.9) | 38 (3.1) | 733 (59.6) | 362 (29.4) | |
| Pre-pregnancy body mass index | |||||
| <30 kg/m2 | 95 (8.0) | 41 (3.5) | 710 (60.1) | 335 (28.4) | |
| ≥30 kg/m2 | 25 (8.4) | 9 (3.0) | 171 (57.2) | 94 (31.4) | |
| Interpregnancy interval | |||||
| No previous pregnancies | 33 (8.5) | 14 (3.6) | 237 (61.1) | 104 (26.8) | |
| ≤12 months | 34 (11.1) | 14 (4.6) | 170 (55.6) | 88 (28.8) | |
| >12 months | 50 (6.4) | 22 (2.8) | 475 (61.1) | 230 (29.6) | |
| Total | 121 (8.0) | 51 (3.4) | 904 (59.6) | 440 (29.0) | |
| Gastroschisis | Folic acid-containing supplement usec | ||||
| Yes | 295 (31.5) | 288 (30.7) | 170 (18.1) | 185 (19.7) | |
| No | 129 (30.8) | 131 (31.3) | 87 (20.8) | 72 (17.2) | |
| Maternal smokingc | |||||
| Yes | 145 (30.2) | 140 (29.2) | 95 (19.8) | 100 (20.8) | |
| No | 272 (31.3) | 280 (32.3) | 163 (18.8) | 153 (17.6) | |
| Pre-pregnancy body mass index | |||||
| <30 kg/m2 | 408 (31.9) | 386 (30.1) | 247 (19.3) | 240 (18.7) | |
| ≥30 kg/m2 | 19 (25.7) | 28 (37.8) | 14 (18.9) | 13 (17.6) | |
| Interpregnancy interval | |||||
| No previous pregnancies | 206 (30.0) | 215 (31.3) | 126 (18.3) | 140 (20.4) | |
| ≤12 months | 87 (36.7) | 68 (28.7) | 41 (17.3) | 41 (17.3) | |
| >12 months | 127 (30.3) | 127 (30.3) | 92 (22.0) | 73 (17.4) | |
| Total | 441 (31.4) | 430 (30.6) | 269 (19.2) | 264 (18.8) | |
a
Row percentages.
b
Numbers vary because of missing values.
c
Month before conception through the second month of pregnancy.