During 1 January 2013-31 December 2019, 3,945,102 pregnant women were screened for syphilis and 4271 who delivered at gestational age of 28 weeks or more and were registered in Information System of PMTCT of Syphilis Management of Jiangxi Province were enrolled. Among these women, 61 women were excluded from the study because of delivering multiple pregnancy (46) or lacking of treatment information (15), thus resulting in 4210 women included in the final analyses (Fig. 1). Characteristics of syphilis-seropositive pregnant women between the treated and untreated group are shown in Table 1. Women in the treated group were younger than those in the untreated group (P < 0.001). Significant differences in education (P < 0.001), employment (P = 0.007), marital status (P = 0.028), nulliparas (P < 0.001), and history of syphilis infection (P < 0.001) were observed between the two groups. In addition, compared with women in the treated group, those in the untreated group had a smaller proportion of attending the first antenatal care in first trimester (28.6% vs. 41.0%; P < 0.001) and being in the latent stage (76.6% vs. 84.5%; P < 0.001).
Table 1
Characteristics of syphilis-seropositive pregnant women with respect to treatment status
Characteristics | Treated (n = 2846) | Untreated (n = 1364) | P |
Age (y) | 28.50 ± 6.00 | 29.23 ± 6.15 | < 0.001 |
Ethnicity of Han | 2745 (96.5) | 1329 (97.4) | 0.091 |
Education | | | < 0.001 |
Primary school and illiteracy | 424 (14.9) | 266 (19.5) | |
Junior high school | 1630 (57.3) | 729 (53.4) | |
Senior high school | 521 (18.3) | 243 (17.8) | |
College and above | 182 (6.4) | 66 (4.8) | |
Unknown | 89 (3.1) | 60 (4.4) | |
Employment | | | 0.007 |
Unemployed | 1616 (56.8) | 744 (54.5) | |
Worker without regular pay | 656 (23.0) | 345 (25.3) | |
Ordinary employee | 188 (6.6) | 62 (4.5) | |
Other | 386 (13.6) | 213 (15.6) | |
Marital status | | | 0.028 |
Single | 147 (5.2) | 52 (3.8) | |
First marriage | 2295 (80.6) | 1144 (83.9) | |
Other | 404 (14.2) | 168 (12.3) | |
Nulliparas | 872 (30.6) | 214 (15.7) | < 0.001 |
History of syphilis infection | 1091 (38.3) | 397 (29.1) | < 0.001 |
Time of the first antenatal care | | | < 0.001 |
First trimester | 1166 (41.0) | 390 (28.6) | |
Second trimester | 842 (29.6) | 218 (16.0) | |
Third trimester | 592 (20.8) | 492 (36.1) | |
Unknown | 246 (8.6) | 264 (19.4) | |
Maternal syphilis stage | | | < 0.001 |
Latent stage | 2406 (84.5) | 1041 (76.6) | |
Primary stage | 120 (4.2) | 40 (2.9) | |
Secondary stage | 22 (0.8) | 7 (0.5) | |
Tertiary stage | 12 (0.4) | 9 (0.7) | |
Unknown | 286 (10.6) | 267 (19.6) | |
Nontreponemal serum test titer | | | 0.019 |
< 1:8 | 2022 (71.0) | 968 (71.0) | |
≥ 1:8 | 804 (28.3) | 374 (27.4) | |
Unknown | 20 (0.7) | 22 (1.6) | |
Data are expressed as mean ± SD or number (percentage). |
Significant values are in bold font. |
When pregnancy outcomes were analyzed according to treatment status, the infants born to untreated mothers were at significantly higher risk for stillbirth (aOR = 1.74, 95% CI, 1.01-3.00, P = 0.045), preterm birth (aOR = 1.27, 95% CI, 1.02–1.59, P = 0.034) and LBW (aOR = 1.44; 95% CI, 1.11–1.86, P = 0.006) than those born to the treated mothers after adjustment for maternal age, education, employment, marital status and parity (Table 2).
Table 2
Pregnancy outcomes of syphilis-seropositive pregnant women with respect to treatment status
Pregnancy outcomes | Treateda (n = 2846) | Untreated (n = 1364) | OR (95% CI)b | P |
Stillbirth | 32 (1.1) | 25 (1.8) | 1.74 (1.01-3.00) | 0.045 |
Preterm birth | 238 (8.4) | 143 (10.5) | 1.27 (1.02–1.59) | 0.034 |
Low birth weight | 161 (5.7) | 107 (7.8) | 1.44 (1.11–1.86) | 0.006 |
Birth defects | 12 (0.4) | 7 (0.5) | 1.22 (0.47–3.16) | 0.686 |
Asphyxia | 47 (1.7) | 23 (1.7) | 0.99 (0.59–1.65) | 0.973 |
Pneumonia | 14 (0.5) | 8 (0.6) | 1.16 (0.48–2.82) | 0.749 |
Neonatal CS | 45 (1.6) | 30 (2.3) | 1.39 (0.86–2.25) | 0.176 |
OR = odds ratio; CI = confidence interval; CS = congenital syphilis. |
Significant values are in bold font. |
a Reference group. | | | | |
b Adjusted for age, education, employment, marital status and parity. |
To further investigate the influence of adequate treatment and initiation time of treatment during pregnancy on pregnancy outcomes, 2846 treated women were included in the analysis. We found that a significantly higher risk of stillbirth (aOR = 3.68; 95% CI, 1.62–8.34, P = 0.002), preterm birth (aOR = 2.26; 95% CI, 1.71-3.00, P < 0.001), LBW (aOR = 2.23; 95% CI, 1.59–3.14, P < 0.001) and CS (aOR = 3.63; 95% CI, 1.80–7.31, P < 0.001) in infants born to mothers treated inadequately than those treated adequately after adjusting for maternal age, education, employment, marital status and parity (Table 3). Compared with infants exposed to mothers who initiated treatment in the first trimester, those who initiated treatment in the third trimester had an increased risk of stillbirth (aOR = 4.48; 95% CI, 1.31–15.30, P = 0.017), preterm birth (aOR = 2.34; 95% CI, 1.61–3.40, P < 0.001) and LBW (aOR = 3.25; 95% CI, 1.97–5.37, P < 0.001) after adjustment for maternal age, education, employment, marital status and parity. Besides, no infant born to mothers who initiated treatment in the first trimester was diagnosis with CS (Table 4).
Table 3
Pregnancy outcomes with respect to adequate treatment status among treatment group
Pregnancy outcomes | Treated adequatelya (n = 1547) | Treated inadequately (n = 1299) | OR (95% CI)b | P |
Stillbirth | 8 (0.5) | 24 (1.8) | 3.68 (1.62–8.34) | 0.002 |
Preterm birth | 86 (5.6) | 152 (11.7) | 2.26 (1.71-3.00) | < 0.001 |
Low birth weight | 58 (3.7) | 103 (7.9) | 2.23 (1.59–3.14) | < 0.001 |
Birth defects | 6 (0.4) | 6 (0.5) | 1.09 (0.34–3.49) | 0.889 |
Asphyxia | 21 (1.4) | 26 (2.0) | 1.46 (0.81–2.64) | 0.210 |
Pneumonia | 8 (0.5) | 6 (0.5) | 0.82 (0.28–2.44) | 0.719 |
Neonatal CS | 11 (0.7) | 34 (2.7) | 3.63 (1.80–7.31) | < 0.001 |
OR = odds ratio; CI = confidence interval; CS = congenital syphilis. |
Significant values are in bold font. |
a Reference group. |
b Adjusted for age, education, employment, marital status and parity. |
Table 4
Pregnancy outcomes with respect to initiation time of treatment among treatment group
Group | Stillbirth | Preterm birth | Low birth weight | Birth defects | Asphyxia | Pneumonia | Neonatal CS |
Initiated treatment in the first trimester (≤ 12 weeks)a | 3 (0.4) | 40 (5.9) | 20 (2.9) | 1 (0.1) | 8 (1.2) | 5 (0.7) | 0 (0) |
Initiated treatment in the second trimester (13 weeks − 27 weeks) | 6 (0.6) | 48 (5.2) | 37 (4.0) | 6 (0.6) | 13 (1.4) | 4 (0.4) | 11 (1.2) |
OR (95% CI)b | 1.41 (0.35–5.69) | 0.89 (0.58–1.37) | 1.35 (0.78–2.36) | 4.24 (0.51–35.39) | 1.20 (0.49–2.92) | 0.57 (0.15–2.13) | / |
P | 0.634 | 0.588 | 0.287 | 0.183 | 0.685 | 0.399 | / |
Initiated treatment in the third trimester (≥ 28 weeks) | 23 (1.9) | 150 (12.2) | 104 (8.4) | 5 (0.4) | 26 (2.1) | 5 (0.4) | 34 (2.8) |
OR (95% CI)b | 4.48 (1.31–15.30) | 2.34 (1.61–3.40) | 3.25 (1.97–5.37) | 2.48 (0.28–21.86) | 1.84 (0.81–4.17) | 0.46 (0.13–1.69) | 2.26 (1.11–4.61)c |
P | 0.017 | < 0.001 | < 0.001 | 0.413 | 0.142 | 0.243 | 0.025 |
P for trend | 0.003 | < 0.001 | < 0.001 | 0.622 | 0.109 | 0.252 | < 0.001 |
OR = odds ratio; CI = confidence interval; CS = congenital syphilis. |
Significant values are in bold font. |
a Reference group. |
b Adjusted for age, education, employment, marital status and parity. |
c Initiated treatment in the second trimester as reference group |
To clarify whether initiation time of treatment influenced its adequacy, we performed a further analysis and found that significantly higher rates of adequacy when treatment was initiated in the first (84.8%) and second trimester (79.5%) than in the third trimester (18.6%) (P < 0.001) (Table 5).
Table 5
Adequate treatment associated with initiation time
Initiation time of treatment | Treated adequately | Treated inadequately | P |
Initiated treatment in the first trimester (≤ 12 weeks) | 578 (84.8) | 104 (15.2) | < 0.001 |
Initiated treatment in the second trimester (13 weeks–27 weeks) | 739 (79.5) | 191 (20.5) |
Initiated treatment in the third trimester (≥ 28 weeks) | 230 (18.6) | 1004 (81.4) |
Significant values are in bold font. | | | |