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Table 1 Basic characteristics of 505 study participants by interval time

From: Relationship between menstruation status and work conditions in Japan

Number (%) or median (25–75% range)

Less than 11 h of interval time

(n = 37)

11 h and more interval time

(n = 468)

p-valuesa

Age (years)

29 (25–38)

33 (29–38)

0.0101

Smoking (yes)

1 (3%)

19 (4%)

0.684

Body mass index (kg/m2)

19.9 (19.4–22.3)

19.8 (18.6–21.2)

0.1614

Insufficient breakfast (not a well-balanced breakfast or not every morning)

18 (49%)

264 (56%)

0.360

Parity (yes)

5 (14%)

155 (33%)

0.014

Family care demands (yes)

12 (32%)

265 (57%)

0.004

 

Living situation (alone)

10 (27%)

116 (25%)

0.762

Marital status (married)

9 (24%)

249 (53%)

0.001

Living with children (yes)

5 (14%)

161 (34%)

0.009

Satisfaction with present social status (Satisfied)

31 (84%)

383 (82%)

0.767

 

Education (graduate school)

12 (32%)

168 (36%)

0.672

Regular employment (yes)

32 (86%)

315 (67%)

0.015

 

Subjective economic conditions (Upper & Upper middle)

17 (46%)

177 (38%)

0.328

 

Length of time in present status (years)

3.9 (2.7–10.7)

6.7 (3.2–11.8)

0.1634

 

Occupations:

Clerical and related workers

13 (35%)

177 (38%)

0.213

 

Professional and highly technical job

6 (16%)

133 (28%)

 

Teachers at school

12 (32%)

95 (20%)

Others

6 (16%)

63 (13%)

Average interval time (hours/day)

9.5 (8.4–10.3)

14.3 (12.8–16.4)

<0.0001

 

Average regular work time (hours/month)

250 (240–280)

170 (140–200)

<0.0001

 

Average extra work time (hours/month)

50 (40–90)

11 (0–34)

<0.0001

 

Average commuting time (hours/day)

1 (1–2)

1 (0–2)

0.0023

  1. aComparison by chi-square test, and Wilcoxon’s rank sum test