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Table 3 Estimated preterm births due to excisional treatment of the cervical transformation zone

From: How many preterm births in England are due to excision of the cervical transformation zone? Nested case control study

   

Estimated births after first treatment (N)

Preterm births

  

Very preterm births

  

(<37 gestational weeks)

(20–31 gestational weeks)

Age at first treatment

Women with excisional treatment

Estimated births taking into account length distribution*

Estimated births assuming all excisions ≥10 mm were small

Excess births due to treatments

Estimated births taking into account length distribution

Estimated births assuming all excisions ≥10 mm were small

Excess births due to treatments

N

%

 

<20 single excision

167

1.6

323

31

24

7

8

6

1

20–24 single excision

2355

22.0

4043

395

303

91

104

81

23

25–29 single excision

3417

31.9

4332

428

325

103

111

87

24

30–34 single excision

2907

27.1

1929

176

145

31

45

39

7

35–39 single excision

1865

17.4

343

33

26

7

9

7

2

Total

10711

100 %

10970

1063

823

240

276

219

57