Table 2. Factors associated with preterm birth, low birth weight, SGA, and congenital anomalies.
| Congenital anomaly (n = 6,600) | Low birth weight (n = 6,561) | |||||
| No | Yes | P * | ≥2,500 g | <2,500 g | P * | |
| N (%) or mean (SD) | N (%) or mean (SD) | |||||
| 6,411 (97.1) | 189 (2.9) | 6,116 (93.2) | 445 (6.8) | |||
|
| ||||||
| External radiation dose | 0.188 | 0.811 | ||||
|
| ||||||
| Missing | 3,308 (51.6) | 106 (56.1) | 3,150 (51.5) | 235 (52.8) | ||
| <1 mSv, % | 2,124 (33.1) | 64 (33.9) | 2,032 (33.2) | 141 (31.7) | ||
| 1 to <2 mSv, % | 925 (14.4) | 19 (10.1) | 885 (14.5) | 64 (14.4) | ||
| ≥2 mSv, % | 54 (0.8) | 0 (0.0) | 49 (0.8) | 5 (1.1) | ||
| Maternal age, years | 30.9 (5.0) | 30.6 (5.2) | 0.456 | 30.9 (5.0) | 31.0 (5.2) | 0.458 |
| Child’s sex (male), % | 3,284 (51.3) | 105 (55.9) | 0.221 | 3,168 (51.9) | 183 (41.1) | <0.001 |
| Child’s length, cm | 49.2 (2.1) | 48.5 (3.4) | 0.007 | 49.5 (1.8) | 45.5 (2.8) | <0.001 |
| Child’s weight, g | 3,036 (392.5) | 2,904 (556.8) | 0.002 | 3,097 (327.5) | 2,251 (318.2) | <0.001 |
| Gestational days at delivery, days | 275.7 (10.3) | 272.2 (18.4) | 0.013 | 277.0 (8.3) | 260.6 (18.9) | <0.001 |
| Primiparous, % | 1,628 (25.5) | 44 (23.4) | 0.511 | 1,537 (25.3) | 129 (29.1) | 0.077 |
| Low birth weight (<2,500 g), % | 459 (7.2) | 33 (17.7) | <0.001 | — | — | |
| SGA, % | 520 (8.8) | 24 (13.9) | 0.022 | 290 (5.2) | 228 (54.0) | <0.001 |
| Stillbirth, % | 5 (0.1) | 3 (1.6) | 0.001** | — | — | |
| Preterm birth (<37 weeks), % | 217 (3.6) | 22 (12.6) | <0.001 | 81 (1.4) | 130 (30.7) | <0.001 |
| Forced to change health check-up facility, % | 2,234 (35.2) | 80 (42.6) | 0.038 | 2,117 (35.0) | 156 (35.3) | 0.831 |
| Trimester of pregnancy at earthquake | 0.550 | 0.656 | ||||
| First (2–14 weeks), % | 1,900 (32.3) | 61 (36.3) | 1,830 (32.7) | 128 (30.8) | ||
| Second (14–28 weeks), % | 2,355 (40.1) | 63 (37.5) | 2,229 (39.8) | 174 (41.9) | ||
| Third (≥28 weeks), % | 1,625 (27.6) | 44 (26.2) | 1,537 (27.5) | 113 (27.2) | ||
| Infertility treatment, % | 316 (4.9) | 12 (6.4) | 0.376 | 275 (4.5) | 30 (6.7) | 0.030 |
| Placenta previa, % | 94 (1.5) | 1 (0.5) | 0.286 | 85 (1.4) | 11 (2.5) | 0.066 |
| Hypertensive disorders of pregnancy, % | 202 (3.2) | 5 (2.7) | 0.694 | 164 (2.7) | 46 (10.3) | <0.001 |
| Mental disorders before birth, % | 382 (6.0) | 18 (9.5) | 0.043 | 368 (6.0) | 24 (5.4) | 0.592 |
| Evacuation area, % | 686 (10.7) | 20 (10.6) | 0.959 | 657 (10.7) | 44 (9.8) | 0.573 |
|
| ||||||
| SGA (n = 6,034) | Preterm birth (n = 6,111) | |||||
| ≥−10% | <−10% | P * | ≥37 weeks | <37 weeks | P * | |
| 5,516 (91.4) | 518 (8.6) | 5,899 (96.5) | 212 (3.5) | |||
|
| ||||||
| External radiation dose | 0.103 | 0.335 | ||||
|
| ||||||
| Missing | 2,854 (51.7) | 252 (48.7) | 3,029 (51.4) | 122 (57.6) | ||
| <1 mSv, % | 1,818 (33.0) | 170 (32.8) | 1,954 (33.1) | 60 (28.3) | ||
| 1 to <2 mSv, % | 800 (14.5) | 94 (18.2) | 871 (14.8) | 28 (13.2) | ||
| ≥2 mSv, % | 44 (0.8) | 2 (0.4) | 45 (0.8) | 2 (0.9) | ||
| Maternal age, years | 30.9 (5.0) | 30.5 (5.2) | 0.105 | 30.8 (5.0) | 31.6 (5.4) | 0.040 |
| Child’s sex (male), % | 2,831 (51.3) | 248 (47.9) | 0.134 | 2,983 (50.7) | 120 (56.9) | 0.080 |
| Child’s length, cm | 49.4 (2.0) | 47.1 (2.3) | <0.001 | 49.3 (1.9) | 45.2 (3.7) | <0.001 |
| Child’s weight, g | 3,091 (359.1) | 2,481 (281.6) | <0.001 | 3,065 (359.9) | 2,329 (561.8) | <0.001 |
| Gestational days at delivery, days | 275.7 (10.1) | 276.4 (11.3) | 0.189 | 276.9 (7.9) | 244.5 (18.3) | <0.001 |
| Primiparous, % | 1,465 (26.6) | 107 (20.7) | 0.003 | 1,522 (25.9) | 57 (26.9) | 0.753 |
| Low birth weight (<2,500 g), % (%) | 194 (3.5) | 228 (44.0) | <0.001 | 294 (5.0) | 130 (61.6) | <0.001 |
| SGA, % | 495 (8.5) | 23 (10.9) | 0.222 | |||
| Stillbirth, % | — | — | ||||
| Preterm birth (<37 weeks), % | 188 (3.4) | 23 (4.4) | 0.222 | — | — | |
| Forced to change health check-up facility, % | 1,927 (35.3) | 174 (33.8) | 0.496 | 2,059 (35.2) | 71 (34.5) | 0.822 |
| Trimester of pregnancy at earthquake | 0.360 | 0.179 | ||||
| First (2–14 weeks), % | 1,765 (32.5) | 166 (32.7) | 1,888 (32.5) | 69 (33.7) | ||
| Second (14–28 weeks), % | 2,181 (40.2) | 190 (37.4) | 2,313 (39.8) | 91 (44.4) | ||
| Third (≥28 weeks), % | 1,483 (27.3) | 152 (29.9) | 1,605 (27.6) | 45 (22.0) | ||
| Infertility treatment, % | 259 (4.7) | 27 (5.2) | 0.597 | 277 (4.7) | 13 (6.1) | 0.334 |
| Placenta previa, % | 85 (1.5) | 4 (0.8) | 0.165 | 76 (1.3) | 13 (6.1) | <0.001** |
| Hypertensive disorders of pregnancy, % | 156 (2.8) | 40 (7.7) | <0.001 | 173 (2.9) | 26 (12.3) | <0.001 |
| Mental disorders before birth, % | 344 (6.2) | 24 (4.6) | 0.145 | 360 (6.1) | 12 (5.7) | 0.791 |
| Evacuation area, % | 582 (10.6) | 49 (9.5) | 0.438 | 624 (10.6) | 18 (8.5) | 0.330 |
SGA, small for gestational age.
*t-test was used for continuous variables and chi-square tests was used for other categorical variables.
**Fisher’s exact test was used for other categorical variables.