Table 1 Association between number of ultrasound scans and socio-demographic and clinical variables (n/%)

Maternal age (years)

< 0.001

≤ 23 years

36/22.2

53/32.7

73/45.1

24-31 years

249/23.2

512/47.6

314/29.2

≥ 32 years

313/28.7

544/50.0

232/21.3

Maternal education level (years)

< 0.001

≤ 5 education years

95/58.6

58/35.8

9/5.6

6-8 education years

451/42.0

512/47.6

112/10.4

≥ 9 education years

317/29.1

573/52.6

199/18.3

Husband education level (years)

< 0.001

≤ 5 education years

49/30.2

93/57.4

20/12.3

6-8 education years

233/21.7

675/62.8

167/15.5

≥ 9 education years

191/17.5

655/60.1

243/22.3

Family annual income (yuan)

< 0.001

≤ 3000 yuan

117/72.2

34/21.0

11/6.8

3001-7499 yuan

614/57.1

294/27.3

167/15.5

≥ 7500 yuan

556/51.1

359/33.0

174/16.0

Antenatal care (n/%) *

< 0.001

Yes

17/2.0

294/35.4

519/62.5

No

145/9.7

781/52.2

570/38.1

Adverse outcomes in previous pregnancy (n/%)

0.001

Yes

11/6.7

54/33.1

98/60.1

No

151/7.0

1021/47.2

991/45.8

Pregnancy complication (n/%)

< 0.001

Yes

15/2.9

208/40.8

287/56.3

No

147/8.1

867/47.7

802/44.2

Primiparity (n/%)

< 0.001

Yes

74/4.7

681/42.9

834/52.5

No

88/11.9

394/53.5

255/34.6

Preterm delivery (n/%)

0.710

Yes

11/7.9

68/48.6

61/43.6

No

151/6.9

1007/46.1

1028/47.0

Large for date infant (n/%)

< 0.001

Yes

31/14.0

93/41.9

98/44.1

No

131/6.2

982/46.7

991/47.1

Caesarean section (n/%)

< 0.001

Yes

56/4.4

509/39.9

710/55.7

No

106/10.1

566/53.9

379/36.1