Syphilis during pregnancy increases the chance of negative outcomes in newborns

To consider a newborn healthy, it is checked the height, weight and gestational age it reached before birth. However, these parameters can be affected by the presence of other factors during pregnancy. Now, a new study by a research team from the Center for Data and Knowledge Integration for Health (Cidacs/Fiocruz Bahia) shows that the occurrence of gestational syphilis also affects the health of newborns and increases the likelihood that the child will be underweight, considered small for its age or born prematurely.

Published in the latest issue of the International Journal of Gynecology and Obstetrics, the research shows that children born to pregnant women with syphilis had a higher prevalence of prematurity (14.45%), low birth weight (13.40%), and being considered small for gestational age (11.66%), compared to those born to pregnant women without the disease (who had a prevalence of 10.63%, 7.14% and 7.34% of the same outcomes, respectively).

Based on this data, the research team estimated that, when compared to people who had not been diagnosed with the disease, pregnant women with syphilis had an 88% increased likelihood of their children having low birth weight, 53% of being considered small for their gestational age and 35% of prematurity.

Syphilis can be transmitted from a pregnant woman to her child through what is known as "vertical transmission". It can occur at any time during pregnancy, and it is not necessary for the person infected to be in a more aggravated clinical state for the infection to occur. "Treatment and early diagnosis play a crucial role in preventing congenital syphilis and thus the occurrence of these negative outcomes," comments Helena Benes, researcher associated with Cidacs/Fiocruz.

The study considered data on more than 17 million live births, obtained from the Live Birth Information System (SINASC), linked to syphilis notification data from the Notifiable Diseases Information System (SINAN).

In 2015, Brazil was considered by the Pan American Health Organization (PAHO) to be one of the fifteen priority countries for reducing cases of congenital syphilis. However, between 2011 and 2021, the occurrence of these cases was around 20 times higher than the target of 1 case per 500 live births. "These results highlight the

need for adequate screening and treatment of gestational syphilis to mitigate the risk of adverse birth outcomes," she weighted.

The role of prenatal care against syphilis

The Ministry of Health's official recommendation is to test for syphilis during prenatal care, preferably in the first quarter of pregnancy. Once diagnosed, the disease is treated with injection of penicillin. The patient's recovery is determined by the test known as VDRL (Venereal Disease Research Laboratory), which, by indicating the viral titer [the presence of antibodies], shows how advanced the infection is.

With this information in mind, the research team also estimated the likelihood of negative outcomes in pregnant women diagnosed with syphilis but treated, and in those who did not receive treatment. Taking the group of uninfected women as a reference, the study concludes that the likelihood of negative outcomes for the child increases proportionally in relation to the VDRL viral titer In other words, the more advanced the infection, the more likely it is that the child will have developmental problems.

Additionally, analysis of the groups by the number of prenatal appointments showed that children of pregnant women who had fewer than six appointments were also more likely to have adverse outcomes. "We noticed that strengthening policies for the adequate treatment of gestational syphilis and carrying out prenatal appointments would already contribute significantly to reducing cases of adverse outcome," adds Helena.

During prenatal care, it is possible to monitor whether the pregnant woman, and the child, are gaining adequate weight during pregnancy, or whether there are any complications. These factors can be managed and prevented during pregnancy. The researcher emphasizes that prenatal care is the time for proper counseling of pregnant women. For example, this is the time when people are warned about the importance of involving their partner in the treatment to avoid re-infection. "Just the fact that a woman goes for prenatal care already helps to prevent and treat problems during pregnancy and, later on, even in the child."

Other studies by the research team have also looked at other outcomes associated with congenital syphilis. According to another article, published in 2023, the mortality risk for children affected by the disease is up to twice that of those who have not had the disease.