Maternal age (yr) |
32 (30–35) |
33 (31–36) |
<0.001* |
Primiparity (%) |
41.5 (292/704) |
51.2 (387/756) |
<0.001** |
Body mass index (kg/m2) before pregnancy |
20.7
(19.3–22.8) |
21.3 (19.5–24.2) |
<0.001* |
History of preterm delivery (%) |
11.5 (81/704) |
9.39 (71/756) |
0.186** |
Multifetal pregnancy |
|
|
|
Twin (%) |
18.6 (131/704) |
18.7 (141/756) |
0.983** |
Triplet (%) |
1.4 (10/704) |
2.1 (16/756) |
0.315** |
Pregnancy by in vitro fertilization-embryo transfer (%) |
15.8
(111/704) |
20.2 (153/756) |
0.027** |
Pregnancy by intrauterine insemination (%) |
2.3 (16/704) |
2.3
(17/756) |
0.972** |
Gestational age at admission (wk) |
28.2 (24.6–32.4) |
29.3
(24.1–33.1) |
0.097* |
Diagnosis at admission |
|
|
|
Preterm premature rupture of membrane (%)
|
39.6 (279/704)
|
40.0 (302/756)
|
0.902**
|
Incompetent internal os of the cervix (%)
|
16.6 (117/704)
|
18.7 (141/756)
|
0.309**
|
Cerclage (%) |
9.0 (63/704) |
11.2 (85/756) |
0.147** |
Preterm labor (%) |
41.3 (291/704) |
35.7 (270/756) |
0.027** |
Short cervical length (%) |
2.6 (18/704) |
8.5 (64/756) |
<0.001** |
Prior antibiotic treatment (%) |
13.9 (98/704) |
18.5 (140/756) |
0.018** |