Table 1 Sociodemographic characteristics of participants (N = 15,332)

Age (years)

32.9 ± 5.94

32.8 ± 5.84

33.2 ± 6.44

 First marriage

14,923/97.3

12,519/97.4

2404/96.9

 Remarriage

409/2.7

333/2.6

76/3.1

 Han nationality

11,434/74.6

9137/71.1

2297/92.6

 Minority

3898/25.4

3715/28.9

183/7.4

 East China

8419/54.9

6410/49.9

2009/81.0

 South China

3902/25.5

3709/28.9

193/7.8

 Northwest China

1599/10.4

1523/11.9

76/3.1

 Central China

692/4.5

634/4.9

58/2.3

 Southwest China

343/2.2

321/2.5

22/0.9

 North China

253/1.7

175/1.4

78/3.1

 Northeast China

124/0.8

80/0.6

44/1.8

 city

13,029/85.0

10,937/85.1

2092/84.4

 rural

2303/15.0

1915/14.9

388/15.6

 High school

247/1.6

177/1.4

70/2.8

 College

5230/34.1

4350/33.8

880/35.5

 Bachelor

8582/56.0

7418/57.7

1164/46.9

 Master

1022/6.7

732/5.7

290/11.7

 Doctor

251/1.6

175/1.4

76/3.1

 Healthcare staff

10,885/71.0

10,075/78.4

810/32.7

 Worker, as teacher, civil servant, office worker

2585/16.9

1723/13.4

862/34.8

 Laborer

1088/7.1

589/4.6

499/20.1

 Individual operator

305/2.0

169/1.3

136/5.5

 Farmer

102/0.7

71/0.6

31/1.3

 Soldier

36/0.2

5/0.0

31/1.3

 Freelancer

331/2.2

220/1.7

111/4.5

 5000–10,000

8350/54.5

7190/55.9

1160/46.8

 10,001–20,000

4728/30.8

3889/30.3

839/33.8

 20,001–30,000

1426/9.3

1154/9.0

272/11.0

 >30,000

828/5.4

619/4.8

209/8.4

 Tenancy

1924/12.5

1589/12.4

335/13.5

 Housing with loan

10,389/67.8

8718/67.8

1671/67.4

 Housing without loan

3019/19.7

2545/19.8

474/19.1

 None

3106/20.3

2431/18.9

675/27.2

 One

6660/43.4

5703/44.4

957/38.6

 Two

5566/36.3

4718/36.7

848/34.2