Table 1.

Characteristics included in definitions of onset of labor

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)