Table 3 Association of maternal CRP, C3, C4 and ferritin levels and the risk of PTB in the first trimester

CRP

0.043

 P50 < 11.40

24

68

1

–

1

–

 P50 - P75 (11.40–16.60)

20

34

1.67 (0.80–3.51)

0.175

1.73 (0.81–3.67)

0.154

 P75 > 16.60

24

34

2.13 (1.01–4.50)

0.048

2.16 (1.02–4.56)

0.044

C3

0.045

 P50 < 1222.00

26

68

1

–

 P50 - P75 (1222.00–1369.00)

16

34

1.32 (0.60–2.90)

0.493

1.45 (0.64–3.30)

0.370

 P75 > 1369.00

26

33

2.28 (1.06–4.91)

0.034

2.53 (1.14–5.64)

0.023

C4

0.178

 P50 < 258.50

30

68

1

–

1

–

 P50 - P75 (258.50–309.00)

13

35

0.85 (0.38–1.87)

0.679

0.85 (0.38–1.88)

0.689

 P75 > 309.00

25

33

1.77 (0.88–3.57)

0.111

1.89 (0.93–3.85)

0.079

ferritin

0.107

 P50 < 84.07

27

68

1.00

–

1

–

 P50 - P75 (84.07–138.85)

17

34

1.27 (0.62–2.63)

0.512

1.29 (0.62–2.67)

0.492

 P75 > 138.85

24

34

1.92 (0.92–4.04)

0.084

2.03 (0.95–4.34)

0.067