Table 2 Comparison of the characteristics of participants with completed data vs. without completed data
| Â | Followed-up participants | Drop-out participants | Followed-up vs. Drop-out p-value* | ||||||
|---|---|---|---|---|---|---|---|---|---|
Test (n = 186) | Control (n = 183) | Total (n = 369) | p-value* | Test (n = 110) | Control (n = 110) | Total (n = 220) | p-value* | ||
Age (year, mean ± SD) | 31.2 ± 3.7 | 31.9 ± 4.2 | 31.5 ± 4.0 | 0.765 | 31.0 ± 3.8 | 30.5 ± 4.1 | 30.4 ± 4.4 | 0.449 | < 0.01 |
Gestational age (weeks, mean ± SD) | 14.3 ± 2.7 | 14.5 ± 2.9 | 14.4 ± 2.7 | 0.439 | 14.3 ± 2.5 | 14.3 ± 2.5 | 14.3 ± 2.7 | 0.983 | 0.644 |
Education level (%) | |||||||||
 Junior high school or below | 9.4 | 7.6 | 9.0 | 0.633 | 15.5 | 11.0 | 10.9 | 0.043 | 0.063 |
 Senior high school | 19.2 | 22.4 | 20.4 |  | 20.2 | 37.8 | 27.7 |  | |
 Tertiary education or above | 71.4 | 70.0 | 70.6 |  | 64.3 | 51.2 | 61.4 |  | |
Dental scheme coverage (%) | |||||||||
 No | 57.3 | 59.5 | 61.2 | 0.639 | 67.9 | 68.3 | 63.0 | 0.952 | 0.669 |
 Yes | 42.7 | 40.5 | 38.8 |  | 37.0 | 31.7 | 37.0 |  | |
Monthly household income (HKD, %) | |||||||||
  < $20,000 | 13.1 | 15.7 | 14.7 | 0.205 | 20.2 | 25.6 | 20.1 | 0.438 | 0.320 |
 $20,000- < $30,000 | 18.3 | 18.1 | 19.9 |  | 22.6 | 31.7 | 21.9 |  | |
 $30,000- < $40,000 | 22.1 | 16.2 | 20.4 |  | 20.2 | 14.6 | 15.5 |  | |
 $40,000- < $60,000 | 31.0 | 27.1 | 28.3 |  | 25.0 | 20.7 | 26.0 |  | |
  > $60,000 | 15.5 | 22.9 | 16.6 |  | 11.9 | 7.3 | 16.4 |  | |
Smoking (%) | |||||||||
 No | 95.8 | 96.3 | 96.2 |  0.369 | 94.8 | 95.2 | 95.1 |  0.688 | 0.650 |
 Yes | 4.2 | 3.7 | 3.8 |  | 5.2 | 4.8 | 4.9 |  | |