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Table 3 ORs (95%CI) for the adverse pregnancy outcomes according to the quartiles of urea nitrogen (UN)

From: Serum urea acid and urea nitrogen levels are risk factors for maternal and fetal outcomes of pregnancy: a retrospective cohort study

 

UN (mmol/L) in the second trimester

Ptrend

Per–SD increase

Q1 (< 2.23)

Q2 (2.23–2.50)

Q3 (2.55–3.00)

Q4 (> 3.00)

PROM

 Case/N

88/458

76/352

80/442

69/350

  

 Model 1

1 (ref)

1.16 (0.82, 1.63)

0.93 (0.66, 1.30)

1.03 (0.73, 1.47)

0.838

0.97 (0.86, 1.10)

 Model 2

1 (ref)

1.15(0.82, 1.63)

0.95(0.68, 1.34)

1.05(0.73, 1.50)

0.938

0.98(0.86, 1.11)

PTB

 Case/N

9/458

7/352

12/442

9/350

  

 Model 1

1 (ref)

1.01 (0.37, 2.75)

1.39 (0.58, 3.34)

1.32 (0.52, 3.35)

0.440

1.02 (0.73, 1.40)

 Model 2

1 (ref)

0.98 (0.35, 2.71)

1.36 (0.56, 3.32)

1.26 (0.48, 3.28)

0.500

0.98 (0.71, 1.37)

LBW

 Case/N

8/458

4/352

8/442

9/350

  

 Model 1

1 (ref)

0.65 (0.19, 2.17)

1.04 (0.39, 2.79)

1.49 (0.58, 3.89)

0.349

1.10 (0.77, 1.56)

 Model 2

1 (ref)

0.75(0.22, 2.58)

1.03(0.38, 2.85)

1.58(0.58, 4.29)

0.346

1.12(0.78, 1.61)

SGA

 Case/N

18/458

12/352

27/442

26/350

  

 Model 1

1 (ref)

0.86 (0.41, 1.82)

1.59 (0.86, 2.93)

1.96 (1.06, 3.64)

0.011

1.18 (0.96, 1.46)

 Model 2

1 (ref)

0.90(0.43, 1.92)

1.54(0.83, 2.87)

2.18 (1.16, 4.13)

0.007

1.21(0.98, 1.50)

 

UN (mmol/L) in the third trimester

  

Q1 (< 2.45)

Q2 (2.45–2.90)

Q3 (2.93–3.35)

Q4 (> 3.35)

PROM

 Case/N

87/408

85/455

55/339

86/400

  

 Model 1

1 (ref)

0.85 (0.61, 1.18)

0.72 (0.49, 1.04)

1.01 (0.72, 1.41)

0.874

1.01 (0.89, 1.14)

 Model 2

1 (ref)

0.83 (0.59, 1.16)

0.65 (0.44, 0.96)

0.91 (0.65, 1.29)

0.443

0.97 (0.85, 1.10)

PTB

 Case/N

14/408

8/455

6/339

9/400

  

 Model 1

1 (ref)

0.50 (0.21, 1.21)

0.51 (0.19, 1.33)

0.65 (0.28, 1.51)

0.309

0.74 (0.52, 1.06)

 Model 2

1 (ref)

0.50 (0.21, 1.22)

0.49 (0.18, 1.33)

0.68 (0.28, 1.60)

0.354

0.75 (0.52, 1.08)

LBW

 Case/N

8/408

8/455

4/339

9/400

  

 Model 1

1 (ref)

0.89 (0.33, 2.41)

0.60 (0.18, 2.00)

1.15 (0.44, 3.01)

0.898

1.01 (0.69, 1.45)

 Model 2

1 (ref)

0.82 (0.30, 2.27)

0.54 (0.15, 1.87)

1.06 (0.39, 2.86)

0.996

0.99 (0.68, 1.44)

SGA

 Case/N

15/408

16/455

20/339

32/400

  

 Model 1

1 (ref)

0.96 (0.47, 1.96)

1.64 (0.83, 3.26)

2.28 (1.21, 4.28)

0.002

1.38 (1.13, 1.68)

 Model 2

1 (ref)

0.86 (0.42, 1.79)

1.57 (0.78, 3.16)

2.29 (1.20, 4.36)

0.002

1.35 (1.11,1.64)

  1. PROM premature rupture of membranes, PTB premature birth, LBW low birth weight infants, SGA small for gestational age infants. Model 1: without adjustment. Model 2: adjustment for age, pre–pregnancy BMI, education, smoking status, alcohol status, conception method, number of pregnancies, parity, history of miscarriage, gestational diabetes mellitus and gestational hypertension