Univariable logistic analyses of the risk factors for congenital syphilis
| Variables | OR (95% CI) | p Values |
| Current age | 1.02 (0.93 to 1.11) | 0.736 |
| Education | ||
| Secondary school or below | Reference | |
| High school or above | 0.47 (0.21 to 1.04) | 0.063 |
| History of other STD | ||
| No | Reference | |
| Yes | 0.40 (0.05 to 3.02) | 0.374 |
| Extramarital sexual relations | ||
| No | Reference | |
| Yes | 1.20 (0.57 to 2.54) | 0.637 |
| Numbers of pregnancies | ||
| 1 | Reference | |
| 2 | 1.39 (0.42 to 4.56) | 0.588 |
| 3 | 1.14 (0.33 to 3.90) | 0.834 |
| 4 | 1.27 (0.33 to 4.87) | 0.733 |
| ≥5 | 0.87 (0.15 to 4.91) | 0.872 |
| History of APOs | ||
| No | Reference | |
| Yes | 0.97 (0.36 to 2.60) | 0.948 |
| Stage of maternal syphilis | ||
| Early (<2 years) | 5.01 (2.15 to 11.69) | <0.001 |
| Late (≥2 years or unknown) | Reference | |
| Log (1/T)* | 11.18 (5.16 to 24.24) | <0.001 |
| GW† | 1.1 (1.06 to 1.15) | <0.001 |
| GW×log (1/T)‡ | 1.09 (1.06 to 1.11) | <0.001 |
↵* The values were transformed by the log (the reciprocal of the TRUST titre in mothers).
↵† The gestational week (GW) at treatment for maternal syphilis.
↵‡ The interaction between GW and log (1/T).
APOs, adverse pregnancy outcomes; STD, sexually transmitted disease; TRUST, toluidine red unheated serum test.