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Syphilis is one of the most important complications of pregnancy, as it is one of the most frequent causes of abortion or premature labour. Syphilis is the most common cause of foetal death in the later months of pregnancy, and may be maternal or paternal in origin.

—J. Whitridge Williams (1903)


Syphilis and gonorrhea were prominently mentioned in the first edition of this book, with special consideration for their harmful effects on fetal development. Although Williams confined his discussion to these two infections, today, sexually transmitted diseases (STDs) include chlamydial and trichomonal infections and viral STDs such as hepatitis B, human immunodeficiency virus (HIV), herpes simplex virus (HSV), and human papillomavirus (HPV) infections. In some form, all can be injurious to the mother or fetus and thus should be aggressively sought and treated. In many instances, recommended therapies are provided in guidelines from the Centers for Disease Control and Prevention (CDC) and listed throughout the chapter.

Vertical transmission refers to passage from the mother to her fetus of an infectious agent through the placenta, during labor or delivery, or by breastfeeding. Treatment of most STDs is clearly associated with improved pregnancy outcome and prevention of perinatal morbidity. Logically, education, screening, treatment, and prevention are essential components of prenatal care.


Despite the availability of adequate therapy for decades, syphilis remains a major issue for both mother and fetus. From 2001 through 2015, the primary and secondary syphilis rates have risen almost yearly (Centers for Disease Control and Prevention, 2016c). In the United States in 2015, the combined rate for both of these among women was 1.8 cases per 100,000 persons (de Voux, 2017). For congenital syphilis, after a nadir in 2012, rates have also risen yearly to reach 12.4 cases per 100,000 live births in 2015. Of risks, higher congenital syphilis rates are linked to inadequate prenatal care, black or Hispanic race, and lack of treatment (Su, 2016). Similarly, syphilis remains a significant global health problem, with many countries reporting high numbers of new infections (Newman, 2015; World Health Organization, 2012).

Pathogenesis and Transmission

Syphilis is caused by the spirochetal bacterium Treponema pallidum. Minute abrasions on the vaginal mucosa provide an entry portal, and cervical eversion, hyperemia, and friability raise transmission risk. Spirochetes replicate and then disseminate through lymphatic channels within hours to days. The incubation period is 3 to 4 weeks depending on host factors and inoculum size.

The early stages of syphilis include primary, secondary, and early latent syphilis. These are associated with high spirochete loads, and partner transmission rates approximate 30 to 60 percent (Garnett, 1997; Singh, 1999). In late-stage disease, transmission rates decline because of smaller inoculum sizes.

Maternal syphilis can cause fetal infection by several routes. Spirochetes ...

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