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Risk Factors for Congenital Syphilis and Adverse Pregnancy Outcomes in Offspring of Women With Syphilis in Shenzhen, China: A Prospective Nested Case-Control Study

Qin, Jia-Bi MD, PhD*†; Feng, Tie-Jian MD; Yang, Tu-Bao PhD*; Hong, Fu-Chang MD; Lan, Li-Na MPH; Zhang, Chun-Lai MPH; Yang, Fan MD; Mamady, Keita PhD*; Dong, Willa MPH

Sexually Transmitted Diseases: January 2014 - Volume 41 - Issue 1 - p 13–23
doi: 10.1097/OLQ.0000000000000062
Original Study

Background: Despite existence of a highly effective intervention, maternal syphilis still causes substantial perinatal morbidity and mortality, even in China, where antenatal health services are strong. This study sought to address personal, programmatic, and other risk factors for congenital syphilis (CS) and adverse pregnancy outcomes (APOs) among pregnant women in Shenzhen, China.

Methods: Pregnant women attending antenatal services were offered serologic tests, and those diagnosed as having syphilis were recruited from April 2007 to October 2012. In a nested case-control study for the pregnancy outcomes of syphilis-infected women, we assessed risk factors comparing infants born with CS (group II) and with any APOs (group III) to infants without CS or APOs (group I).

Results: During the 66-month study period, we screened 279,334 pregnant women and identified 838 (0.3%; 95% confidence interval, 0.28%–0.32%) women infected with syphilis. Among infants born to syphilitic mothers, 8.2% (34/417) were diagnosed as having CS and 24.7% (103/417) were diagnosed as having APOs. Compared with group I, maternal baseline titers of nontreponemal antibodies (adjusted odds ratio [aOR], 2.13), stage of syphilis (aOR, 21.56), length of time between the end of the first treatment to childbirth (aOR, 11.93), gestational week at treatment (aOR, 2.63), and fathers’ cocaine use (aOR, 15.44) and syphilis infection status (aORpositive vs. negative, 5.84; aORunknown vs. negative, 5.55) were positively associated with CS, but prenatal care (aOR, 0.11) and complete treatment (aOR, 0.20) were negatively associated with CS. Maternal age (aOR, 1.43), marriage (aOR, 2.41), history of cocaine use (aOR, 3.79) and ectopic pregnancy (aOR, 5.91), baseline titers of nontreponemal antibodies (aOR, 1.30), stage of syphilis (aOR, 8.89), length of time between the end of the first treatment to childbirth (aOR, 2.52), gestational week at treatment (aOR, 1.78), and fathers’ syphilis infection status (aORunknown vs. negative, 2.02) were also positively associated with APOs, but maternal history of syphilis (aOR, 0.44), prenatal care (aOR, 0.29), and complete treatment (aOR, 0.25) were negatively associated with APOs,

Conclusions: Syphilis was an important cause of pregnancy loss and infant disability, particularly among women who did not receive prenatal care or had late or inadequate treatment. These study results can inform antenatal programs on the importance of early syphilis testing and prompt and appropriate treatment. Some strategies targeted at other risk factors areas may be helpful.

Behavioral, obstetric and clinical factors from pregnant women with syphilis and their spouses could create considerable obstacles to the elimination of pregnancy loss. Future strategies for prevention of pregnancy loss from maternal syphilis should be targeted to each factor.

From the *Department of Epidemiology and Health Statistics, School of Public Health, Central South University, Hunan, People’s Republic of China, and †Department of Dermatology and Venereal Disease, Shenzhen Center for Chronic Disease Control and Prevention, Shenzhen, People’s Republic of China

Acknowledgements: The authors thank all patients for their participation in this study. This work was supported by the program of prevention of mother-to-children transmission of syphilis in Shenzhen, China. Funding was provided by the Fundamental Research Funds for the Central Universities of Central South University and Science Research and Innovation Projects of Hunan province in China (project number: 2012zzts029; CX2012B076).

Author disclosure statement: No competing financial interests exist.

Financial support: Jia-Bi Qin was supported by the Fundamental Research Funds for Central South University (2012zzts029) and the Hunan Province Innovation Projects (CX2012B076) of China. This work was also supported by the program of prevention of mother-to-children transmission of syphilis in Shenzhen, China.

Ethical clearance was obtained from the research ethics review committee of Shenzhen Centre for Chronic Disease Control and Prevention. Informed consent was obtained from all participants who signed or fingerprinted the consent form after the aims of the study had been explained to them.

Correspondence: Tie-Jian Feng, MD, Department of Dermatology and STD, Shenzhen Centre for Chronic Disease Control and Prevention, 2021 Buxin Rd, Luohu District, Shenzhen 518020, China. E-mail: fengtiej@126.com. Jia-Bi Qin, PhD, is to be contacted at the Department of Epidemiology and Health Statistics, School of Public Health, Central South University, 110 Xiangya Rd, Changsha, Hunan 410078, China. E-mail: qinjiabi123@163.com.

Received for publication March 30, 2013, and accepted October 17, 2013.

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