Analysis of data on 8 million children in Brazil shows that syphilis exposure during pregnancy increases children's risk of hospitalisation
Children born with syphilis are six times more likely to be admitted to hospital in their first five years of life compared to children not exposed to syphilis from their mother before birth, according to new research.
The study, published in JAMA Network Open, was led by researchers from the London School of Hygiene & Tropical Medicine (LSHTM) and the Center for Data and Knowledge Integration for Health (CIDACS) and used data from the Brazilian Ministry of Health.
Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. Syphilis can also be transmitted from mother to baby during pregnancy.
It's estimated that 50-80% of cases of syphilis in pregnancy result in adverse birth outcomes, including stillbirth, preterm birth and infant death. Children who survive infection may be left with life-long disability including skeletal abnormalities, seizures, deafness and severe infections.
The study followed over eight million children in Brazil who had been exposed to syphilis before they were born. Of these, over 30,000 children had been exposed to syphilis from their mother during pregnancy (maternal syphilis) but were not diagnosed with the infection themselves, and over 36,000 were diagnosed at birth with syphilis infection passed from their mother (congenital syphilis).
Researchers found that children born with congenital syphilis were six times more likely to be hospitalised before the age of five than children who were not exposed. Similarly, babies who were exposed to the infection during development but not diagnosed with the infection themselves were twice as likely to be hospitalised.
The increased risk of hospitalisation was particularly high in the first month of life. Children born with congenital syphilis were 11 times more likely to be hospitalised in the first month compared with babies not exposed.
According to the WHO, syphilis is one of the most common STIs globally, with approximately six million new cases each year. Once considered more common in low- and middle-income countries, rates of syphilis have also been increasing in high-income countries in recent years.
Dr Enny Da Paixao Cruz, lead author of the paper and Associate Professor at LSHTM, said: "Syphilis infections are both preventable and treatable, and yet we continue to see thousands of women and children severely affected by the disease each year.
"Through our study, we've found that all babies exposed to syphilis during their development, regardless of whether they themselves are born with the infection, have worse health outcomes in their first years of life than children who are not exposed. This means that babies may still be significantly impacted by the infection even if their mothers are treated during their pregnancy.
"To improve outcomes for expectant mothers and their babies, public health actions must go beyond testing in pregnancy and focus on preventing syphilis infection in women before they even become pregnant."
Professor Maria Yury Ichihara, senior author of the study, from CIDACS, said: "This study shows that the impact of syphilis during pregnancy goes far beyond birth. Even when congenital infection isn't detected, children exposed in utero face significantly higher risks of hospitalisation in early childhood - this is a call to action for better prevention, screening, and long-term care strategies."
The authors acknowledged limitations in their study including the fact it was based on administrative data meaning some clinical data was unavailable, and risks around potential misclassification due to the way maternal syphilis was defined and congenital syphilis was diagnosed.
The study was funded by Wellcome.
Publication
Paixão et al, Syphilis Exposure During Pregnancy and Childhood Hospital Admissions in Brazil. JAMA Network Open. DOI: 10.1001/jamanetworkopen.2025.7471
