Table 2 ORs (95%CI) for the adverse pregnancy outcomes according to the quartiles of urea acid (UA)
|  | UA (μmol/L) in the second trimester | P trend | Per–SD increase | |||
|---|---|---|---|---|---|---|
Q1 (< 179.8) | Q2 (179.8–205.4) | Q3 (205.5–234.7) | Q4 (> 234.7) | |||
PROM | ||||||
 Case/N | 76/401 | 83/401 | 75/400 | 79/400 |  |  |
 Model 1 | 1 (ref) | 1.16 (0.79, 1.58) | 0.99 (0.69, 1.41) | 1.05 (0.74, 1.49) | 0.960 | 1.01 (0.89, 1.14) |
 Model 2 | 1 (ref) | 1.10 (0.77, 1.57) | 1.01 (0.70, 1.44) | 1.02 (0.71, 1.46) | 0.821 | 1.01 (0.88, 1.14) |
PTB | ||||||
 Case/N | 5/401 | 10/401 | 9/400 | 13/400 |  |  |
 Model 1 | 1 (ref) | 2.03 (0.69, 5.98) | 1.82 (0.61, 5.49) | 2.66 (0.94, 7.53) | 0.089 | 1.27 (0.94, 1.72) |
 Model 2 | 1 (ref) | 2.02 (0.67, 6.04) | 1.85 (0.61, 5.65) | 2.70 (0.94, 7.80) | 0.095 | 1.27 (0.94, 1.73) |
LBW | ||||||
 Case/N | 7/401 | 8/401 | 6/400 | 8/400 |  |  |
 Model 1 | 1 (ref) | 1.15 (0.41, 3.19) | 0.86 (0.29, 2.57) | 1.15 (0.41, 3.20) | 0.928 | 1.01 (0.70, 1.46) |
 Model 2 | 1 (ref) | 1.19 (0.42, 3.42) | 0.99 (0.32, 3.08) | 1.35 (0.47, 3.89) | 0.669 | 1.09 (0.75, 1.61) |
SGA | ||||||
 Case/N | 20/401 | 16/401 | 23/400 | 24/400 |  |  |
 Model 1 | 1 (ref) | 0.79 (0.40, 1.55) | 1.16 (0.63, 2.15) | 1.22 (0.66, 2.24) | 0.334 | 1.14 (0.92, 1.41) |
 Model 2 | 1 (ref) | 0.87 (0.44, 1.72) | 1.36 (0.73, 2.56) | 1.47 (0.78, 2.75) | 0.123 | 1.22 (0.98, 1.51) |
|  | UA (μmol/L) in the third trimester |  |  | |||
|---|---|---|---|---|---|---|
Q1 (< 240.1) | Q2 (240.2–277.7) | Q3 (277.8–323.0) | Q4 (> 323.0) | |||
PROM | ||||||
 Case/N | 69/407 | 74/394 | 76/406 | 94/395 |  |  |
 Model 1 | 1 (ref) | 1.13 (0.79, 1.63) | 1.12 (0.79, 1.62) | 1.53 (1.08, 2.17) | 0.022 | 1.20 (1.07, 1.36) |
 Model 2 | 1 (ref) | 1.15 (0.80, 1.66) | 1.10 (0.76, 1.58) | 1.48 (1.04, 2.10) | 0.047 | 1.18 (1.04, 1.33) |
PTB | ||||||
 Case/N | 13/407 | 7/394 | 7/406 | 10/395 |  |  |
 Model 1 | 1 (ref) | 0.55 (0.22, 1.39) | 0.53 (0.21, 1.35) | 0.79 (0.34, 1.82) | 0.531 | 1.11 (0.81, 1.53) |
 Model 2 | 1 (ref) | 0.55 (0.21, 1.40) | 0.56 (0.22, 1.43) | 0.79 (0.34, 1.84) | 0.565 | 1.12 (0.82, 1.53) |
LBW | ||||||
 Case/N | 11/407 | 4/394 | 8/406 | 6/395 |  |  |
 Model 1 | 1 (ref) | 0.36 (0.12, 1.17) | 0.72 (0.29, 1.82) | 0.56 (0.20, 1.52) | 0.378 | 0.99 (0.68, 1.43) |
 Model 2 | 1 (ref) | 0.35 (0.11, 1.12) | 0.71 (0.28, 1.84) | 0.52 (0.19, 1.45) | 0.338 | 0.97 (0.67, 1.41) |
SGA | ||||||
 Case/N | 14/407 | 23/394 | 19/406 | 27/395 |  |  |
 Model 1 | 1 (ref) | 1.74 (0.88, 3.43) | 1.38 (0.68, 2.79) | 2.06 (1.06, 3.99) | 0.069 | 1.28 (1.04, 1.57) |
 Model 2 | 1 (ref) | 1.76 (0.89, 3.49) | 1.42 (0.69, 2.87) | 1.99 (1.01, 3.89) | 0.066 | 1.24 (1.01, 1.53) |