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Table 1 Characteristics included in definitions of onset of labor

From: Diagnosing onset of labor: a systematic review of definitions in the research literature

Characteristic included N (%)
Type of labor defined  
 Latent 3 (5)
 First stage 11 (18)
 Active 22 (35)
 Labor (unspecified) 15 (24)
 More than one of the above 11 (18)
Cervical dilation 42 (68)
In latent phase labor  
  < 2 cm 1 (2)
 3–4 cm 3 (5)
  > 4 cm 7 (11)
In active labor  
  ≥ 2 cm 2 (3)
 3–4 cm 10 (16)
  > 4 cm 14 (23)
In first stage labor  
 3–4 cm 4 (6)
  > 4 cm 1 (2)
In unspecified labor  
  ≥ 2 cm 2 (3)
 3–4 cm 2 (3)
  > 4 cm 2 (3)
Cervical effacement 12 (19)
Regular painful contractions 44 (71)
Frequency of contractions 12 (19)
 1 in 8–10 min 3 (5)
 2 in 10 min or five minutes apart 3 (5)
 3 in 10 min 5 (8)
 1 every 3–5 mins 2 (3)
Other physiological symptoms 7 (11)
Rationale for definition  
 Referred to women’s reports of onset or routine clinical practice 11 (18)
 Cited Friedman 8 (13)
 Cited Gross 4 (6)
 Cited textbooks 3 (5)
 Cited another study 2 (3)