Table 1.
Demographic information and other characteristics of Mothers in cases and control groups (categorical variables)
| Items | Preterm delivery | Total N (%) |
|
|---|---|---|---|
| Control N (%) |
Case N (%) |
||
| All participants | 1795 (73.0) | 668 (27.0) | |
| Age(years) | |||
| < 35 | 1674 (94.0) | 588 (88.8) | 2262 (92.6) |
| ≥ 35 | 107 (6.0) | 74 (11.2) | 181 (7.4) |
| Level of Education | |||
| Illiterate | 76 (4.2) | 39 (5.9) | 115 (4.7) |
| Primary | 366 (20.4) | 172 (25.8) | 538 (21.9) |
| Guidance | 449 (25.0) | 126 (18.9) | 575 (23.4) |
| High school | 689 (38.4) | 251 (37.7) | 940 (38.2) |
| Collegiate | 213 (11.9) | 78 (11.7) | 291 (11.8) |
| Ethnic | |||
| Tork | 366 (21.7) | 38 (6.1) | 404 (17.5) |
| Lor | 73 (4.3) | 37 (5.9) | 110 (4.8) |
| Fars | 1083 (64.1) | 479 (76.8) | 1562 (67.5) |
| Kord | 29 (1.7) | 23 (3.7) | 52 (2.2) |
| Arab | 20 (1.2) | 6 (1.0) | 26 (1.1) |
| Balooch | 11 (0.7) | 6 (1.0) | 17 (0.7) |
| Torkaman | 99 (5.9) | 32 (5.1) | 131 (5.7) |
| Else | 9 (0.5) | 3 (0.5) | 12 (0.5) |
| Occupation | |||
| Housewife | 1610 (90.9) | 610 (91.9) | 2220 (91.2) |
| Employee | 110 (6.2) | 40 (6.0) | 150 (6.2) |
| Farmer& carpet weaver | 31 (1.8) | 7 (1.1) | 38 (1.6) |
| Other | 20 (1.1) | 7 (1.1) | 27 (1.1) |
| Place of Residence | |||
| Urban | 694 (39.7) | 314 (48.1) | 1008 (42.0) |
| Rural | 1053 (60.3) | 339 (51.9) | 1392 (58.0) |
| Abortion history | |||
| Yes | 154 (8.6) | 102 (15.3) | 256 (10.4) |
| No | 1641 (91.4) | 566 (84.7) | 2207 (89.6) |
| Stillbirth history | |||
| Yes | 104 (5.8) | 122 (18.3) | 226 (9.2) |
| No | 1691 (94.2) | 546 (81.7) | 2237 (90.8) |
| Cesarean history | |||
| Yes | 205 (11.4) | 86 (12.9) | 291 (11.8) |
| No | 1590 (88.6) | 582 (87.1) | 2172 (88.2) |
| Gap pregnancy(years) | |||
| Upper than 3 | 537 (30.4) | 189 (28.9) | 726 (30.0) |
| Lower than 1 | 74 (4.2) | 55 (8.4) | 129 (5.3) |
| 1–3 | 496 (28.1) | 153 (23.4) | 649 (26.8) |
| Primary pregnancy | 661 (37.4) | 257 (39.3) | 918 (37.9) |
| Consanguineous marriage | |||
| Yes | 494 (28.1) | 205 (31.3) | 699 (29.0) |
| No | 1263 (71.9) | 450 (68.7) | 1713 (71.0) |
| Supplements Consumption | |||
| Yes, use regular | 1449 (81.8) | 535 (80.5) | 1984 (81.4) |
| Yes, use not regular | 213 (12.0) | 91 (13.7) | 304 (12.5) |
| Use not | 109 (6.2) | 39 (5.9) | 148 (6.1) |
| BMI | |||
| Normal | 893 (53.6) | 292 (48.7) | 1185 (52.3) |
| Underweight | 313 (18.8) | 126 (21.0) | 439 (19.4) |
| Overweight | 329 (19.7) | 121 (20.2) | 450 (19.9) |
| Obesity grade1 | 101 (6.1) | 55 (9.2) | 156 (6.9) |
| Obesity grade 2 | 31 (1.9) | 5 (0.8) | 36 (1.6) |
| Regular Cycles of period | |||
| Yes | 1564 (90.2) | 536 (82.7) | 2100 (88.2) |
| No | 170 (9.8) | 112 (17.3) | 282 (11.8) |