Notification rates for syphilis in women of reproductive age and congenital syphilis in Australia, 2011–2021: a retrospective cohort analysis of national notifications data

Objectives To estimate notification rates for infectious syphilis in women of reproductive age and congenital syphilis in Australia. Study design Retrospective cohort study; analysis of national infectious syphilis and enhanced congenital syphilis surveillance data. Setting, participants Women aged 15–44 years diagnosed with infectious syphilis, and babies with congenital syphilis, Australia, 2011–2021. Main outcome measures Numbers and rates of infectious syphilis notifications, by Indigenous status and age group; numbers and rates of congenital syphilis, by Indigenous status of the infant; antenatal care history for mothers of infants born with congenital syphilis. Results During 2011–2021, 5011 cases of infectious syphilis in women aged 15–44 years were notified. The notification rate for Aboriginal and Torres Strait Islander women rose from 56 (95% confidence interval [CI], 45–65) cases per 100 000 in 2011 to 227 (95% CI, 206–248) cases per 100 000 population in 2021; for non‐Indigenous women, it rose from 1.1 (95% CI, 0.8–1.4) to 9.2 (95% CI, 8.4–10.1) cases per 100 000 population. The notification rate was higher for Aboriginal and Torres Strait Islander women than for non‐Indigenous women (incidence rate ratio [IRR], 23.1; 95% CI, 19.7–27.1), lower for 15–24‐ (IRR, 0.7; 95% CI, 0.6–0.9) and 35–44‐year‐old women (IRR, 0.6; 95% CI, 0.5–0.7) than for 25–34‐year‐old women, and higher in remote regions than in major cities (IRR, 2.7; 95% CI, 2.2–3.8). During 2011–2021, 74 cases of congenital syphilis were notified, the annual number increasing from six in 2011 to a peak of 17 in 2020; the rate was consistently higher among Aboriginal and Torres Strait Islander infants than among non‐Indigenous infants (2021: 38.3 v 2.1 per 100 000 live births). The mothers of 32 infants with congenital syphilis (43%) had not received antenatal care. Conclusions The number of infectious syphilis notifications for women of reproductive age increased in Australia during 2011–2021, as did the number of cases of congenital syphilis. To avert congenital syphilis, antenatal screening of pregnant women, followed by prompt treatment for infectious syphilis when diagnosed, needs to be improved.