Expectant mothers who are infected with syphilis can transmit the disease through the placenta to their unborn infants. Congenital syphilis is a severe, disabling, and often life-threatening condition for the infant. Nearly half of all children infected with syphilis during gestation die shortly before or after birth.

Infants who survive develop early-stage and late-stage symptoms of syphilis if not treated. Early-stage symptoms include irritability, failure to thrive, and nonspecific fever. Some infants develop a rash and lesions (sores) on the borders of the mouth, anus, and genitalia (called condyloma lata).

Some of these lesions may resemble the wart-like lesions of adult syphilis. A small percentage of infants have a watery nasal discharge (sniffles) and a saddle nose deformity resulting from infection in the cartilage of the nose. Bone lesions are common, especially in the upper arm (humerus).

Later signs appear as tooth abnormalities (Hutchinson teeth), bone changes (saber shins), neurological involvement, blindness, and deafness. Despite the fact that this disease can be cured with antibiotics if caught early, rising rates of syphilis amongst pregnant women in United States have recently increased the number of infants born with congenital syphilis.