Which of the following represents a significant risk during early latent syphilis infection?

During early latent syphilis infection, the risk of fetal transmission is significant, which is why the first choice is the correct answer. Syphilis can be particularly dangerous for a developing fetus, especially in the absence of treatment, as it can lead to vertical transmission where the infection is passed from the mother to the fetus. The reported risk of fetal transmission during this stage of syphilis can indeed be as high as 40%, making it critical for pregnant individuals to be screened and treated for syphilis to prevent complications.

The other choices present risks that, while they may be relevant to syphilis in certain contexts, do not capture the primary concern during early latent infection. The risk of mortality, congenital defects, and preterm birth can be associated with untreated syphilis, but they are generally not as high in relation to fetal transmission compared to the figure provided in the first option. Thus, understanding the risks of vertical transmission emphasizes the importance of prompt diagnosis and treatment in managing syphilis during pregnancy.