Table 1 Maternal baseline characteristics with respect to preconception status of reproductive tract infection
Characteristics | RTI-infected | RTI-uninfected | p-value |
|---|---|---|---|
No. of pregnancies (%) | 2438 (4.22) | 55,270 (95.78) | Â |
Age, years |  |  |  < 0.001 |
 20–24 | 966 (39.62) | 25,796 (46.67) |  |
 25–29 | 993 (40.73) | 21,849 (39.53) |  |
 30–34 | 308 (12.63) | 5449 (9.86) |  |
 35–49 | 171 (7.01) | 2176 (3.94) |  |
BMI, kg/m2 |  |  |  < 0.001 |
 < 18.5 | 326 (13.37) | 8292 (15.01) |  |
 18.5–23.9 | 1757 (72.07) | 40,448 (73.18) |  |
 24–27.9 | 308 (12.63) | 5579 (10.09) |  |
 ≥ 28 | 47 (1.93) | 951 (1.72) |  |
Ethnicity | Â | Â | 0.055 |
 Han | 2307 (94.63) | 52,759 (95.46) |  |
 Others | 131 (5.37) | 2511 (4.54) |  |
Education |  |  |  < 0.001 |
 Primary or below | 160 (6.56) | 2368 (4.28) |  |
 Middle school | 1096 (44.95) | 24,532 (44.39) |  |
 High school | 536 (21.99) | 13,758 (24.89) |  |
 College or above | 646 (26.50) | 14,612 (26.44) |  |
Place of residence | Â | Â | 0.005 |
 Non-agricultural | 699 (28.67) | 14,433 (26.11) |  |
 Agricultural | 1739 (71.33) | 40,837 (73.89) |  |
Occupation |  |  |  < 0.001 |
 Peasant | 1004 (41.18) | 24,768 (44.81) |  |
 labor worker | 249 (10.21) | 5670 (10.26) |  |
 Merchant | 253 (10.38) | 5975 (10.81) |  |
 service staff | 82 (3.36) | 1957 (3.54) |  |
 Housewife | 184 (7.55) | 3308 (5.99) |  |
 Civil servant | 414 (16.98) | 8448 (15.28) |  |
 Others | 252 (10.34) | 5144 (9.31) |  |
Smoking | Â | Â | 0.004 |
 No | 2413 (98.97) | 54,958 (99.44) |  |
 Yes | 25 (1.03) | 312 (0.56) |  |
Passive smoking | Â | Â | 0.582 |
 No | 2060 (84.50) | 46,926 (84.90) |  |
 Yes | 378 (15.50) | 8344 (15.10) |  |
Alcohol | Â | Â | 0.339 |
 No | 2295 (94.13) | 52,276 (94.58) |  |
 Yes | 143 (5.87) | 2994 (5.42) |  |
Gravidity |  |  |  < 0.001 |
 0 | 838 (34.37) | 26,948 (48.76) |  |
 ≥ 1 | 1600 (65.63) | 28,322 (51.24) |  |
Parity |  |  |  < 0.001 |
 0 | 1511 (61.98) | 38,957 (70.48) |  |
 ≥ 1 | 927 (38.02) | 16,313 (29.52) |  |
History of preterm birth | Â | Â | 0.945 |
 No | 2433 (99.79) | 55,153 (99.79) |  |
 Yes | 5 (0.21) | 117 (0.21) |  |
History of spontaneous abortion |  |  |  < 0.001 |
 No | 2262 (92.78) | 52,829 (95.58) |  |
 Yes | 176 (7.22) | 2441 (4.42) |  |
History of induced abortion |  |  |  < 0.001 |
 No | 1297 (53.20) | 35,900 (64.95) |  |
 Yes | 1141 (46.80) | 19,370 (35.05) |  |
Hypertension | Â | Â | 0.006 |
 No | 2386 (97.87) | 54,473 (98.56) |  |
 Yes | 52 (2.13) | 797 (1.44) |  |
Interval |  |  |  < 0.001 |
 0–3 months | 1572 (64.74) | 39,591 (72.02) |  |
 4–6 months | 526 (21.66) | 9653 (17.56) |  |
 7–12 months | 330 (13.59) | 5727 (10.42) |  |
 Missing | 10 | 299 |  |