Background Estimates of the current number of pregnant women infected with syphilis (maternal syphilis) are necessary for the global Elimination of Congenital Syphilis initiative such that advocacy, program implementation, and monitoring are based on a clear understanding of the current situation. In addition to understanding morbidity in pregnant women, an accurate estimate of maternal syphilis is also the cornerstone of calculations of the burden of adverse outcomes associated with syphilis in pregnancy.

Methods A MEDLINE search from January 2003 to September 2010 was conducted to identify studies of syphilis prevalence in women attending antenatal care with the following inclusion criteria: sample size of at least 100, use of both reaginic and non-reaginic tests, English language, and no apparent selection bias. Methods are similar to those used by Schmid et al in 2007 to estimate maternal syphilis, except that current estimates include Europe and North America, and will be compared with syphilis seropositivity data reported by countries through the WHO HIV Universal Access reporting system for 2008 through 2010 (reported data may or may not use both reaginic and non-reaginic tests). Global and regional estimates will be based on country data where available, and where not available, a regional pregnancy-weighted mean based on live births (per United Nations Population Division) and known country seropositivity will be used. Country and regional estimates will be validated by WHO regional advisors to assess if estimates are reasonable.

Results Studies on approximately 35 of 193 countries (18%) met the inclusion criteria for the MEDLINE search, and 96 countries (50%) reported seropositivity in either 2008 or 2009; additional reported data for 2010 will be available in May 2011, at which time estimates will be completed.

Conclusions Data on maternal syphilis are available in recent published literature for only a small proportion of countries. Therefore, global and regional estimates of maternal syphilis must rely on alternative data sources such as the WHO HIV Universal Access reporting system. Increased efforts are required globally to highlight the importance of having sufficient high-quality data to guide implementation of congenital syphilis elimination efforts.