Table 1 Characteristics of included studies

Farb et al. 1983 [26]

USA

Prospective cohort

31 (7)

Examination or nitrazine positive or fern test positive

20 to 36

NR

Yes

Yes

CRP

HCA and funisitis

5/24 (21)

Hawrylyshyn et al. 1983 [27]

Canada

Prospective cohort

54 (2)

Nitrazine positive or pooling of AF

20 to 34

None

Yes

Selective

CRP

HCA

26/52 (50)

Ismail et al. 1985 [28]

USA

Prospective cohort

100 (0)

Pooling of AF or nitrazine positive

26 to 35

NR

No

No

CRP

HCA and funisitis

63/100 (63)

Fisk et al. 1987 [29]

Saudi Arabia

Prospective cohort

55 (4)

Speculum examination—pooling of AF

26 to 36

NR

Selective, < 34 weeks

Selective, < 32 weeks

CRP

HCA

30/51 (59)

Danielian 1991 [30]

NR

Prospective cohort

17 (6)

NR

26–? (preterm)

NR

NR

NR

CRP

HCA

4/11 (36)

Yoon et al. 1996 [31]

South Korea

Prospective cohort

91 (28)

Pooling on speculum examination and nitrazine positive and fern test positive

20 to 37

NR

NR

NR

CRP

HCA and funisitis

35/63 (56)

Torbe 2007 [32]

?Poland

Prospective cohort

48 (0)

NR

24 to 34

Yes

Yes

None

CRP, PCT

HCA

14/48 (29)

Murtha et al. 2007 [33]

USA

Prospective cohort

122 (15)

Pooling of AF and nitrazine positive and ferning positive

22 to 34

Yes (all)

Selective (23 to 34 weeks)

NR

IL6

Funisitis

54/107 (50)

Smith et al. 2012 [34]

USA

Retrospective cohort

73 (0)

NR

20–37

Selective

Selective

NR

CRP

HCA

26/73 (36)

Perrone et al. 2012 [35]

Italy

Prospective cohort

66 (0)

Speculum exam; IGFBP-1 test

24 to 33

Yes

Yes

Yes

CRP

HCA and funisitis

24/66 (36)

Gulati et al. 2012 [36, 37]

India

Prospective cohort

45 (0)

NR

24 to 34

Yes

Yes

NR

IL6

HCA and funisitis

22/45 (49)

Canzoneri et al. 2012 [38]

USA

Prospective cohort

39 (0)

Pooling of AF and nitrazine positive and ferning positive

22 to 34

Yes (all)

Selective

No

IL6

funisitis

21/39 (54)

Oludag et al. 2014 [39]

Turkey

Prospective cohort

32 (0)

Speculum examination

24 to 34

Yes

Yes

NR

CRP, PCT

HCA

13/32 (41)

Aksakal et al. 2014 [40]

Turkey

Prospective cohort

50 (0)

Speculum examination or positive amnisure test

24 to 37

All

Selective, < 34 weeks

None

CRP

HCA and funisitis

24/50 (48)

Ronzino-Dubost et al. 2016 [41]

France

Prospective cohort

44 (14)

Speculum examination; IGFBP-1 test

24 to 34

Yes

Yes

Selective

CRP, PCT

HCA and funisitis

11/30 (37)

Thornburg et al. 2016 [42]

USA

Prospective

48

Speculum examination; fern and nitrazine test

23 to 33⁺⁶

Yes

Yes

Selective

PCT

HCA and funisitis

19/27 (70)

Kim et al. 2016 [43]

South Korea

Retrospective cohort

181 (35)

Pooling of AF on speculum examination

20 to 33⁺⁶

Yes

Yes

NR

CRP

HCA and funisitis

74/146 (51)

Stepan et al. 2016 [44]

Czech Republic

Prospective cohort

427 (41)

Speculum examination; IGFBP1 test when necessary

24 to 36⁺⁶

Yes

Yes

Yes

CRP

HCA and funisitis

238/386(62)

Kayem et al. 2017 [45]

France

Prospective cohort

184 (46)

History and speculum; other bedside test if necessary

< 37

Selective

NR

NR

CRP

HCA

85/138 (62)

Broumand et al. 2018 [46]/Seivani et al. 2017 [47]

Iran

Prospective cohort

48 (?)

Speculum examination; nitrazine and fern test

28 to 33

Yes

NR

NR

PCT

HCA

19/48 (40)

Martinez-Portilla 2019 et al. [48]

Mexico

Prospective cohort

64

Speculum examination, IGFBP-1 test

26 to 36⁺⁶

Yes

Yes

Yes

IL6

HCA

31/47 (66)

Asadi et al. 2019 [49]

Iran

Prospective, cohort

75 (23)

Pooling on speculum, fern and nitrazine tests

24 to 34

Yes

Selective

Selective

CRP, PCT

HCA

29/52 (56)

Park et al. 2019 [50]

South Korea

Retrospective cohort

82

Speculum; nitrazine test

23 to 34

Selective

Selective

Selective

CRP, IL6

HCA and funisitis

35/82 (43)

Totals

902/1717(37)